IIS Admin's - An IIS Admins Tool box !

IIS and .NET 2.0 interview questions

2012-09-12T11:44:00.003+05:30

: This is meant for a 'systems' or 'itpro' type person and not necessarily a developer type individual.

General IIS related questions

How do you isolate and troubleshoot an ASP and / or ASP.NET application?
Isolate using Using Application pool and Troubleshoot using tools like iisapp,debug diagnostics,iisauth
What is your idea of locking down a server?
Use IIS Lockdown Tool to Turn off unnecessary features
How do you feel about having developers or anyone else making changes directly in production? Aka how do you normally handle change management.
Normally The developer Should not be given access to the Production server, The developer has to test the code in a PRE PROD,UAT or TEST environment to test the code ,upon successful testing a change should be raised to deploy the code in PROD environment
What perfmon counters do you find useful in troubleshooting an IIS or related problem.

Check this
Do you have experience in working with web-farms, load-balancing environments?
Webfarms - More than one worker process assigned to a application pool
What is your ideal way of handling content. Remote Storage / NAS (network attached storage) vs. local content and replication. If you use local content and replication what tools do you to use?
FRS - File Replication Service
Are you familiar with DFS?

The Distributed File System (DFS) technologies offer wide area network (WAN)-friendly replication as well as simplified, highly available access to geographically dispersed files. In Windows Server® 2008, DFS is implemented as a role service of the File Services role. The Distributed File System role service consists of two child role services:

DFS Namespaces and DFS Replication
What debugging tools do you use for IIS?
Troubleshoot using tools like iisapp,debug diagnostics,iisauth
What / Where would you put global .NET settings. How would you lock them down?
Do you have any experience with SSL certificates?

Check this SSL info
Do you have experience with machines with multiple IP's and how to handle several sites / applications on a machine.
What is your preference of handling machine accounts? Do you like local vs. Active Directory based accounts.
Do you have experience with working in an AD environment that supports IIS.
Do you have experience with NLB (network load balancing) that comes with IIS.
Server LAN properties
How do you monitor the applications / sites to ensure the uptime is appropriate. This might apply more to a monitoring environment, but it is good to know what to monitor.
Are you familiar with compression and the benefits.
Do you know what MIME types are for?
Map What file extensions should be handled by which application
Do you know how to list all running applications on a server to determine which application pools are owned by what sites. (IISAPP)
Are you familiar with IISState, IIS Debug Diag. SSL Diag, SMTPDiag in the resource kit.
What tools do you use or have experience in load-testing an application.
What are some of the tools provided by MS. WCAT, TinyGet, WAST.
--Check here - WCAT
--- Check here - TinyGet and More
Do you know how to configure host-headers and how they related to DNS.
What is your backup and recovery strategy for IIS
How would you handle migrating to another box?
How do you handle changes in IIS, scripting or manual changes?
Are you familiar with scripting languages such as VBScript, JScript, Powershell.
Are you familiar with IISCfg and related scripts such as adsutil
Do you have experience supporting multiple environments of IIS (different domains, dev / test /integration / production)
Are you familiar with ways to connect to remote databases such as db2, oracle, sql server
Do you know the differences between anonymous, integrated, basic, digest authentication.
What is your preferred method of publishing content? FTP? FrontPage? WebDAV? Folder copy? Publish to a staging machine and replicate to the content source either on a nas or individual nodes.
Are you familiar with the other services in SMTP, FTP?
Do you know how to configure a smarthost?
Does the built-in FTP service support host-headers?
Do you know the benefits of using a COM+ package vs. Regsvr32
What certain local group is necessary if it is configured as a application pool user.
Do you know how to check a COM+ component to ensure it will not leak memory.

.NET 2.0

Can you run the 1.1 and 2.0 on the same box? What are the limitations.
Can you explain what the '/bin' folder is used for.
Do you know what user instancing is.
Do you know the difference between precompiled applications and publishing the source code.
Do you have any experience with partial trust or CAS (code access security)
What types of things cause an appdomain or application pool recycle.
What are the new folders in .NET 2.0 and what are they used for.
How / why does the machine key need to be the same across all machines in a web-farm.

IIS7

What makes the IUSR account unique in IIS7 vs. previous versions.
What are some of the new ways of troubleshooting, Logging in IIS7
What are the major benefits of IIS7? (FREB, Integrated Pipeline, IUSR same on all w2k8 boxes, Shared configuration, Modular architecture, configuration changes

Differences Between IIS 6 and IIS 70 and 7.5

2012-09-12T11:29:00.002+05:30

The concepts in both IIS versions are generally the same with the exception of WAS introduced in
IIS 7+.With reference to the following diagrams, the class/ object denoted in Green (Http.sys) runs in
Kernel mode while the rest run in User mode.

IIS 6

The concepts are denoted in the following UML Class diagram:

The delegation model is captured in the following UML Sequence diagram:

IIS 7

The concepts are denoted in the following UML Class diagram:

The delegation model is captured in the following UML Sequence diagram:

What are the new features in IIS7?

2012-09-12T11:04:00.000+05:30

1. Simple, Configurable Command Line Setup

· Install only the IIS components needed to run your site

Example: start /w pkgmgr /l:log.etw /iu:IIS-WebServerRole;IIS-WebServer;IIS-CommonHttpFeatures;IIS-StaticContent;IIS-DefaultDocument;IIS-DirectoryBrowsing;IIS-HttpErrors;IIS-HttpRedirect;IIS-ApplicationDevelopment;IIS-ASPNET;IIS-NetFxExtensibility;IIS-ASP;IIS-ISAPIExtensions;IIS-ISAPIFilter;IIS-ServerSideIncludes;IIS-HealthAndDiagnostics;IIS-HttpLogging;IIS-LoggingLibraries;IIS-RequestMonitor;IIS-HttpTracing;IIS-Security;IIS-ClientCertificateMappingAuthentication;IIS-IISCertificateMappingAuthentication;IIS-RequestFiltering;IIS-IPSecurity;IIS-Performance;IIS-HttpCompressionStatic;IIS-HttpCompressionDynamic;IIS-WebServerManagementTools;IIS-ManagementConsole;IIS-ManagementScriptingTools;IIS-ManagementService;IIS-IIS6ManagementCompatibility;IIS-Metabase;IIS-WMICompatibility;IIS-LegacyScripts;IIS-LegacySnapIn;WAS-WindowsActivationService;WAS-ProcessModel;WAS-NetFxEnvironment;WAS-ConfigurationAPI

2. Great Compatibility Story ·

Most (99%+) ASP and ASP.NET applications just worked.
ü One application encountered breaking change ü Handful of applications required config migration to run in Integrated (We have about 260 applications running on www.microsoft.com as defined by IIS, there are thousands of pages of code that could have broken but didn’t.)
· Integrated Pipeline is the new unified request processing pipeline. Benefits include: ü Allowing services provided by both native and managed modules to apply to all requests, regardless of handler. For example, managed Forms Authentication can be used for all content, including ASP pages, CGIs, and static files. ü Empowering ASP.NET components to provide functionality that was previously unavailable to them due to their placement in the server pipeline. For example, a managed module providing request rewriting functionality can rewrite the request prior to any server processing, including authentication, takes place. ü A single place to implement, configure, monitor and support server features. For example, single module and handler mapping configuration, single custom errors configuration, single url authorization configuration.

· Classic ASP mode allows for easy app migration ü ASP.NET Setup provides a “Classic .NET AppPool” ü For more information on check out the article ASP.Net Integration With IIS7 · Use AppCmd to migrate apps to Integrated mode ü %windir%\system32\inetsrv\APPCMD.EXE migrate config ü

For more information about AppCmd.exe see Getting Started With AppCmd.exe · IIS 6.0 Metabase compatibility layer ü Allows you the run old ADSI scripts ü IIS6.0 Metabase Compatibility module must be installed

3. No More Metabase!

· Clean clear-text schema · IIS settings stored in XML configuration file (applicationHost.config) ü Metabase exists for SMTP/NNTP/FTP only

· Site-wide changes made easily ü Update central applicationHost.config and copy to all web servers ü Replaces our bulky ADSI based script solution for metabase changes

· Microsoft.com considerations ü Careful copying to production servers under load: (Know Thy Environment! When you push out a new applicationHost.config those affected worker process need to reload the new configuration. It comes down to the scope of the change. For example, if you are making a global change that that affectes all the worker processes, and you are heavily dependent on caching then you could cause some grief in your environment as those new configurations are reloaded by the worker processes.)

4. Centralized Configuration

· applicationHost.config stored on UNC share
· Allows us to copy to two (maybe four) servers rather than 80 ü Potential gotcha - managing password changes for account used to connect to config store (This is because that currently you cannot use the UNC share that is running under the Network service, which we use heavily. It currently requires a domain account, which our security policy mandates a periodic password change.)

5. Delegated Configuration

· Admin can now delegate IIS settings to application owner · Settings defined in web.config file in application directory · Example of setting to delegate include: ü System.webServer section of applicationHost.config ü Caching, defaultDocument, httpErrors, security

6. AppCmd and Other New Management Options

· Managing via the UI ü New modular, task-based look and feel ü Moving away from the right-click/properties paradigm · Managing via the Command Line ü AppCmd § Command line utility which replaces adsutil.vbs, iisapp.vbs, and others § Allows command line management of sites, applications, vdirs, apppools, modules, tracing, and more ü Powershell § IIS community creating IIS-specific Powershell cmdlets · MSCOM Considerations ü AppCmd limitations – no remote ü No IIS provider for Powershell

7. Failed Request Tracing

· Buffers the trace events for requests and flushes them to disk if they meet your failure criteria · Captures trace data while you’re sleeping · Very little perf impact when targeting failing requests · Quick test: Enabling tracing for all file extensions and errors results in approx 5% fewer requests/sec at full stress load (please don’t do this in production) · View Currently Executing Requests via AppCmd ü appcmd list requests (for all request) ü appcmd list requests /apppool.name:DefaultAppPool REQUEST "3e00000080012675" (url:GET /casestudies/casestudy.aspx?casestudyid=201269, time:2954 msec, client:127.0.0.1) · New Task Scheduler ü Trigger tasks on events

8. Request Filtering

· No more URLScan · settings in applicationHost.config · Gotcha for Microsoft.com: If filename includes “+” then allowDoubleEscaping must be set to “true” ü · Allow or disallow specific file extensions and verbs ü · DenyURLSequences ü ü · RequestLimits ü maxAllowedContentLength="1000000“ ü maxUrl="260“ ü maxQueryString="2048" 9. UNC Content · Simplified content synchronization · Reduced H/W footprint (potentially less cost) ü Common industry pain point 10. Output Caching of Dynamic Content · Fewer off-box calls to backend dependencies · Significant performance gains · Simple WCAT (Web Capacity Analysis Tool) Stress Test against www.microsoft.com/en/us/default.aspx Not appropriate for all applications (e.g. not effective for those with very personalized output)

IIS Interview Questions And Answers

2012-09-12T10:58:00.007+05:30

1. In which process does IIS runs (was asking about the EXE file)

inetinfo.exe is the Microsoft IIS server running, handling ASP.NET requests among other things. When an ASP.NET request is received (usually a file with .aspx extension), the ISAPI filter aspnet_isapi.dll takes care of it by passing the request to the actual worker process aspnet_wp.exe.

2. Where are the IIS log files stored?

C:WINDOWSsystem32LogfilesW3SVC1
OR
c:winntsystem32LogFilesW3SVC1

3. What are the different IIS authentication modes in IIS 5.0 and Explain? Difference between basic and digest authentication modes?

IIS provides a variety of authentication schemes:

• Anonymous (enabled by default)
• Basic
• Digest
• Integrated Windows authentication (enabled by default)
• Client Certificate Mapping

Anonymous
Anonymous authentication gives users access to the public areas of your Web site without prompting them for a user name or password. Although listed as an authentication scheme, it is not technically performing any client authentication because the client is not required to supply any credentials. Instead, IIS provides stored credentials to Windows using a special user account, IUSR_machinename. By default, IIS controls the password for this account. Whether or not IIS controls the password affects the permissions the anonymous user has. When IIS controls the password, a sub authentication DLL (iissuba.dll) authenticates the user using a network logon. The function of this DLL is to validate the password supplied by IIS and to inform Windows that the password is valid, thereby authenticating the client. However, it does not actually provide a password to Windows. When IIS does not control the password, IIS calls the LogonUser() API in Windows and provides the account name, password and domain name to log on the user using a local logon. After the logon, IIS caches the security token and impersonates the account. A local logon makes it possible for the anonymous user to access network resources, whereas a network logon does not.
Basic Authentication
IIS Basic authentication as an implementation of the basic authentication scheme found in section 11 of the HTTP 1.0 specification.
As the specification makes clear, this method is, in and of itself, non-secure. The reason is that Basic authentication assumes a trusted connection between client and server. Thus, the username and password are transmitted in clear text. More specifically, they are transmitted using Base64 encoding, which is trivially easy to decode. This makes Basic authentication the wrong choice to use over a public network on its own.
Basic Authentication is a long-standing standard supported by nearly all browsers. It also imposes no special requirements on the server side — users can authenticate against any NT domain, or even against accounts on the local machine. With SSL to shelter the security credentials while they are in transmission, you have an authentication solution that is both highly secure and quite flexible.
Digest Authentication
The Digest authentication option was added in Windows 2000 and IIS 5.0. Like Basic authentication, this is an implementation of a technique suggested by Web standards, namely RFC 2069 (superceded by RFC 2617).
Digest authentication also uses a challenge/response model, but it is much more secure than Basic authentication (when used without SSL). It achieves this greater security not by encrypting the secret (the password) before sending it, but rather by following a different design pattern — one that does not require the client to transmit the password over the wire at all.
Instead of sending the password itself, the client transmits a one-way message digest (a checksum) of the user’s password, using (by default) the MD5 algorithm. The server then fetches the password for that user from a Windows 2000 Domain Controller, reruns the checksum algorithm on it, and compares the two digests. If they match, the server knows that the client knows the correct password, even though the password itself was never sent. (If you have ever wondered what the default ISAPI filter “md5filt” that is installed with IIS 5.0 is used for, now you know.
Integrated Windows Authentication
Integrated Windows authentication (formerly known as NTLM authentication and Windows NT Challenge/Response authentication) can use either NTLM or Kerberos V5 authentication and only works with Internet Explorer 2.0 and later.
When Internet Explorer attempts to access a protected resource, IIS sends two WWW-Authenticate headers, Negotiate and NTLM.
• If Internet Explorer recognizes the Negotiate header, it will choose it because it is listed first. When using Negotiate, the browser will return information for both NTLM and Kerberos. At the server, IIS will use Kerberos if both the client (Internet Explorer 5.0 and later) and server (IIS 5.0 and later) are running Windows 2000 and later, and both are members of the same domain or trusted domains. Otherwise, the server will default to using NTLM.
• If Internet Explorer does not understand Negotiate, it will use NTLM.
So, which mechanism is used depends upon a negotiation between Internet Explorer and IIS.
When used in conjunction with Kerberos v5 authentication, IIS can delegate security credentials among computers running Windows 2000 and later that are trusted and configured for delegation. Delegation enables remote access of resources on behalf of the delegated user.
Integrated Windows authentication is the best authentication scheme in an intranet environment where users have Windows domain accounts, especially when using Kerberos. Integrated Windows authentication, like digest authentication, does not pass the user’s password across the network. Instead, a hashed value is exchanged.
Client Certificate Mapping
A certificate is a digitally signed statement that contains information about an entity and the entity’s public key, thus binding these two pieces of information together. A trusted organization (or entity) called a Certification Authority (CA) issues a certificate after the CA verifies that the entity is who it says it is. Certificates can contain different types of data. For example, an X.509 certificate includes the format of the certificate, the serial number of the certificate, the algorithm used to sign the certificate, the name of the CA that issued the certificate, the name and public key of the entity requesting the certificate, and the CA’s signature. X.509 client certificates simplify authentication for larger user bases because they do not rely on a centralized account database. You can verify a certificate simply by examining the certificate.

4. IIS Isolation Levels?

Internet Information Server introduced the notion “Isolation Level”, which is also present in IIS4 under a different name. IIS5 supports three isolation levels, that you can set from the Home Directory tab of the site’s Properties dialog:
• Low (IIS Process): ASP pages run in INetInfo.Exe, the main IIS process, therefore they are executed in-process. This is the fastest setting, and is the default under IIS4. The problem is that if ASP crashes, IIS crashes as well and must be restarted (IIS5 has a reliable restart feature that automatically restarts a server when a fatal error occurs).
• Medium (Pooled): In this case ASP runs in a different process, which makes this setting more reliable: if ASP crashes IIS won’t. All the ASP applications at the Medium isolation level share the same process, so you can have a web site running with just two processes (IIS and ASP process). IIS5 is the first Internet Information Server version that supports this setting, which is also the default setting when you create an IIS5 application. Note that an ASP application that runs at this level is run under COM+, so it’s hosted in DLLHOST.EXE (and you can see this executable in the Task Manager).
• High (Isolated): Each ASP application runs out-process in its own process space, therefore if an ASP application crashes, neither IIS nor any other ASP application will be affected. The downside is that you consume more memory and resources if the server hosts many ASP applications. Both IIS4 and IIS5 supports this setting: under IIS4 this process runs inside MTS.EXE, while under IIS5 it runs inside DLLHOST.EXE.
When selecting an isolation level for your ASP application, keep in mind that out-process settings – that is, Medium and High – are less efficient than in-process (Low). However, out-process communication has been vastly improved under IIS5, and in fact IIS5′s Medium isolation level often deliver better results than IIS4′s Low isolation. In practice, you shouldn’t set the Low isolation level for an IIS5 application unless you really need to serve hundreds pages per second.

IIS 7.0 Architecture

2011-04-13T16:07:00.000+05:30

Introduction

Internet Information Services (IIS) 7 provides a new request-processing architecture that includes:

A new service, Windows Process Activation Service (WAS), which enables sites to use protocols other than HTTP and HTTPS.
A Web server engine that can be customized by adding or removing modules.
A new approach to processing requests, integrating the request-processing pipelines from IIS and ASP.NET.

This article describes the components, modules, and request-processing architecture in the following sections:

IIS 7 Components

IIS 7 contains several components that perform important functions for the application and Web server roles in Windows Server® 2008 (IIS 7.0) and Windows Server 2008 R2 (IIS 7.5). Each component has responsibilities, such as listening for requests made to the server, managing processes, and reading configuration files. These components include protocol listeners, such as HTTP.sys, and services, such as World Wide Web Publishing Service (WWW service) and Windows Process Activation Service (WAS).

Protocol Listeners

Protocol listeners receive protocol-specific requests, send them to IIS for processing, and then return responses to requestors. For example, when a client browser requests a Web page from the Internet, the HTTP listener, HTTP.sys, picks up the request and sends it to IIS for processing. Once IIS processes the request, HTTP.sys returns a response to the client browser.
By default, IIS 7 provides HTTP.sys as the protocol listener that listens for HTTP and HTTPS requests. HTTP.sys was introduced in IIS 6.0 as an HTTP-specific protocol listener for HTTP requests. HTTP.sys remains the HTTP listener in IIS 7, but includes support for Secure Sockets Layer (SSL).
To support services and applications that use protocols other than HTTP and HTTPS, you can use technologies such as Windows Communication Foundation (WCF). WCF has listener adapters that provide the functionality of both a protocol listener and a listener adapter. Listener adapters are covered later in this document. For more information about WCF, see Windows Communication Foundation on MSDN.

Hypertext Transfer Protocol Stack (HTTP.sys)

The HTTP listener is part of the networking subsystem of Windows operating systems, and it is implemented as a kernel-mode device driver called the HTTP protocol stack (HTTP.sys). HTTP.sys listens for HTTP requests from the network, passes the requests onto IIS for processing, and then returns processed responses to client browsers.
In IIS 6.0, HTTP.sys replaced Windows Sockets API (Winsock), which was a user-mode component used by previous versions of IIS to receive HTTP requests and send HTTP responses. IIS 7 continues to rely on HTTP.sys for HTTP requests.
HTTP.sys provides the following benefits:

Kernel-mode caching. Requests for cached responses are served without switching to user mode.
Kernel-mode request queuing. Requests cause less overhead in context switching because the kernel forwards requests directly to the correct worker process. If no worker process is available to accept a request, the kernel-mode request queue holds the request until a worker process picks it up.
Request pre-processing and security filtering.

World Wide Web Publishing Service (WWW service)

In IIS 7, functionality that was previously handled by the World Wide Web Publishing Service (WWW Service) alone is now split between two services: WWW Service and a new service, Windows Process Activation Service (WAS). These two services run as LocalSystem in the same Svchost.exe process, and share the same binaries.
Note You may also see the WWW Service referred to as W3SVC in documentation.

How WWW Service works in IIS 6.0

In IIS 6.0, WWW Service manages the following main areas in IIS:

HTTP administration and configuration
Process management
Performance monitoring

HTTP Administration and Configuration

The WWW Service reads configuration information from the IIS metabase and uses that information to configure and update the HTTP listener, HTTP.sys. In addition, WWW service starts, stops, monitors, and manages worker processes that process HTTP requests.

Performance Monitoring

The WWW Service monitors performance and provides performance counters for Web sites and for the IIS cache.

Process Management

The WWW Service manages application pools and worker processes, such as starting, stopping, and recycling worker processes. Additionally, the WWW Service monitors the health of the worker processes, and invokes rapid fail detection to stop new processes from starting when several worker processes fail in a configurable amount of time.

How the WWW Service works in IIS 7

In IIS 7, the WWW service no longer manages worker processes. Instead, the WWW Service is the listener adapter for the HTTP listener, HTTP.sys. As the listener adapter, the WWW Service is primarily responsible for configuring HTTP.sys, updating HTTP.sys when configuration changes, and notifying WAS when a request enters the request queue.
Additionally, the WWW Service continues to collect the counters for Web sites. Because performance counters remain part of the WWW Service, they are HTTP specific and do not apply to WAS.

Windows Process Activation Service (WAS)

In IIS 7, Windows Process Activation Service (WAS) manages application pool configuration and worker processes instead of the WWW Service. This enables you to use the same configuration and process model for HTTP and non-HTTP sites.
Additionally, you can run WAS without the WWW Service if you do not need HTTP functionality. For example, you can manage a Web service through a WCF listener adapter, such as NetTcpActivator, without running the WWW Service if you do not need to listen for HTTP requests in HTTP.sys. For information about WCF listener adapters and about how to host WCF applications in IIS 7 by using WAS, see Hosting in WCF on MSDN.

Configuration Management in WAS

On startup, WAS reads certain information from the ApplicationHost.config file, and passes that information to listener adapters on the server. Listener adapters are components that establish communication between WAS and protocol listeners, such as HTTP.sys. Once listener adapters receive configuration information, they configure their related protocol listeners and prepare the listeners to listen for requests.
In the case of WCF, a listener adapter includes the functionality of a protocol listener. So, a WCF listener adapter, such as NetTcpActivator, is configured based on information from WAS. Once NetTcpActivator is configured, it listens for requests that use the net.tcp protocol. For more information about WCF listener adapters, see WAS Activation Architecture on MSDN.
The following list describes the type of information that WAS reads from configuration:

Global configuration information
Protocol configuration information for both HTTP and non-HTTP protocols
Application pool configuration, such as the process account information
Site configuration, such as bindings and applications
Application configuration, such as the enabled protocols and the application pools to which the applications belong

If ApplicationHost.config changes, WAS receives a notification and updates the listener adapters with the new information.

Process Management

WAS manages application pools and worker processes for both HTTP and non-HTTP requests. When a protocol listener picks up a client request, WAS determines if a worker process is running or not. If an application pool already has a worker process that is servicing requests, the listener adapter passes the request onto the worker process for processing. If there is no worker process in the application pool, WAS will start a worker process so that the listener adapter can pass the request to it for processing.
Note: Because WAS manages processes for both HTTP and non-HTTP protocols, you can run applications with different protocols in the same application pool. For example, you can develop an application, such as an XML service, and host it over both HTTP and net.tcp.

IIS 7 Modules

IIS 7 provides a new architecture that is different from previous versions of IIS. Instead of keeping the majority of functionality within the server itself, IIS 7 includes a Web server engine in which you can add or remove components, called modules, depending on your needs.
Modules are individual features that the server uses to process requests. For example, IIS uses authentication modules to authenticate client credentials, and cache modules to manage cache activity.
The new architecture provides the following advantages over previous versions of IIS:

You can control which modules you want on the server.
You can customize a server to a specific role in your environment.
You can use custom modules to replace existing modules or to introduce new features.

The IIS 7 architecture also improves security and simplifies administration. By removing unnecessary modules, you reduce the server's attack surface and memory footprint, which is the amount of memory that server worker processes use on the machine. You also eliminate the need to manage features that are unnecessary for your sites and applications.

Native Modules

The following sections describe the native modules that are available with a full installation of IIS 7. You can remove them or replace them with custom modules, depending on your needs.

HTTP Modules

Several modules in IIS 7 perform tasks specific to Hypertext Transfer Protocol (HTTP) in the request-processing pipeline. HTTP modules include modules to respond to information and inquiries sent in client headers, to return HTTP errors, to redirect requests, and more.

Module Name	Description	Resource
CustomErrorModule	Sends default and configured HTTP error messages when an error status code is set on a response.	Inetsrv\Custerr.dll
HttpRedirectionModule	Supports configurable redirection for HTTP requests.	Inetsrv\Redirect.dll
ProtocolSupportModule	Performs protocol-related actions, such as setting response headers and redirecting headers based on configuration.	Inetsrv\Protsup.dll
RequestFilteringModule	Added in IIS 7.5. Filters requests as configured to control protocol and content behavior.	Inetsrv\modrqflt.dll
WebDAVModule	Added in IIS 7.5. Allows more secure publishing of content by using HTTP over SSL.	Inetsrv\WebDAV.dll

Security Modules

Several modules in IIS 7 perform tasks related to security in the request-processing pipeline. In addition, there are separate modules for each of the authentication schemes, which enable you to select modules for the types of authentication you want on your server. There are also modules that perform URL authorization, and a module that filters requests.

Module Name	Description	Resource
AnonymousAuthenticationModule	Performs Anonymous authentication when no other authentication method succeeds.	Inetsrv\Authanon.dll
BasicAuthenticationModule	Performs Basic authentication.	Inetsrv\Authbas.dll
CertificateMappingAuthenticationModule	Performs Certificate Mapping authentication using Active Directory.	Inetsrv\Authcert.dll
DigestAuthenticationModule	Performs Digest authentication.	Inetsrv\Authmd5.dll
IISCertificateMappingAuthenticationModule	Performs Certificate Mapping authentication using IIS certificate configuration.	Inetsrv\Authmap.dll
RequestFilteringModule	Performs URLScan tasks such as configuring allowed verbs and file name extensions, setting limits, and scanning for bad character sequences.	Inetsrv\Modrqflt.dll
UrlAuthorizationModule	Performs URL authorization.	Inetsrv\Urlauthz.dll
WindowsAuthenticationModule	Performs NTLM integrated authentication.	Inetsrv\Authsspi.dll
IpRestrictionModule	Restricts IPv4 addresses listed in the ipSecurity list in configuration.	Inetsrv\iprestr.dll

Content Modules

Several modules in IIS 7 perform tasks related to content in the request-processing pipeline. Content modules include modules to process requests for static files, to return a default page when a client doesn't specify a resource in a request, to list the contents of a directory, and more.

Module Name	Description	Resource
CgiModule	Executes Common Gateway Interface (CGI) processes to build response output.	Inetsrv\Cgi.dll
DefaultDocumentModule	Attempts to return a default document for requests made to the parent directory.	Inetsrv\Defdoc.dll
DirectoryListingModule	Lists the contents of a directory.	Inetsrv\dirlist.dll
IsapiModule	Hosts ISAPI extension DLLs.	Inetsrv\Isapi.dll
IsapiFilterModule	Supports ISAPI filter DLLs.	Inetsrv\Filter.dll
ServerSideIncludeModule	Processes server-side includes code.	Inetsrv\Iis_ssi.dll
StaticFileModule	Serves static files.	Inetsrv\Static.dll
FastCgiModule	Supports FastCGI, which provides a high-performance alternative to CGI.	Inetsrv\iisfcgi.dll

Compression Modules

Two modules in IIS 7 perform compression in the request-processing pipeline.

Module Name	Description	Resource
DynamicCompressionModule	Compresses responses and applies Gzip compression transfer coding to responses.	Inetsrv\Compdyn.dll
StaticCompressionModule	Performs pre-compression of static content.	Inetsrv\Compstat.dll

Caching Modules

Several modules in IIS 7 perform tasks related to caching in the request-processing pipeline. Caching improves the performance of your Web sites and Web applications by storing processed information, such as Web pages, in memory on the server, and then reusing that information in subsequent requests for the same resource.

Module Name	Description	Resource
FileCacheModule	Provides user mode caching for files and file handles.	Inetsrv\Cachfile.dll
HTTPCacheModule	Provides kernel mode and user mode caching in HTTP.sys.	Inetsrv\Cachhttp.dll
TokenCacheModule	Provides user mode caching of user name and token pairs for modules that produce Windows user principals.	Inetsrv\Cachtokn.dll
UriCacheModule	Provides user mode caching of URL information.	Inetsrv\Cachuri.dll

Logging and Diagnostics Modules

Several modules in IIS 7 perform tasks related to logging and diagnostics in the request-processing pipeline. The logging modules support loading of custom modules and passing information to HTTP.sys. The diagnostics modules follow and report events during request processing.

Module Name	Description	Resource
CustomLoggingModule	Loads custom logging modules.	Inetsrv\Logcust.dll
FailedRequestsTracingModule	Supports the Failed Request Tracing feature.	Inetsrv\Iisfreb.dll
HttpLoggingModule	Passes information and processing status to HTTP.sys for logging.	Inetsrv\Loghttp.dll
RequestMonitorModule	Tracks requests currently executing in worker processes and reports information with Runtime Status and Control Application Programming Interface (RSCA).	Inetsrv\Iisreqs.dll
TracingModule	Reports events to Microsoft Event Tracing for Windows (ETW).	Inetsrv\Iisetw.dll

Managed Support Modules

A couple of modules in IIS 7 support managed integration in the IIS request-processing pipeline.

Module Name	Description	Resource
ManagedEngine	Provides integration of managed code modules in the IIS request-processing pipeline.	Microsoft.NET\Framework\v2.0.50727\webengine.dll
ConfigurationValidationModule	Validates configuration issues, such as when an application is running in Integrated mode but has handlers or modules declared in the system.web section.	Inetsrv\validcfg.dll

Managed Modules

In addition to native modules, IIS 7 enables you to use managed code modules to extend IIS functionality. Some of the managed modules, such as UrlAuthorization, have a native module counterpart that provides a native alternative to the managed module.
Note Managed modules depend on the ManagedEngine module.
The following table lists the managed modules that are available with a full installation of IIS 7. For more information about the managed modules, see the .NET Framework SDK 2.0 on MSDN.

Module Name	Description	Resource
AnonymousIdentification	Manages anonymous identifiers, which are used by features that support anonymous identification such as ASP.NET profile.	System.Web.Security.AnonymousIdentificationModule
DefaultAuthentication	Ensures that an authentication object is present in the context.	System.Web.Security.DefaultAuthenticationModule
FileAuthorization	Verifies that a user has permission to access the requested file.	System.Web.Security.FileAuthorizationModule
FormsAuthentication	Supports authentication by using Forms authentication.	System.Web.Security.FormsAuthenticationModule
OutputCache	Supports output caching.	System.Web.Caching.OutputCacheModule
Profile	Manages user profiles by using ASP.NET profile, which stores and retrieves user settings in a data source such as a database.	System.Web.Profile.ProfileModule
RoleManager	Manages a RolePrincipal instance for the current user.	System.Web.Security.RoleManagerModule
Session	Supports maintaining session state, which enables storage of data specific to a single client within an application on the server.	System.Web.SessionState.SessionStateModule
UrlAuthorization	Determines whether the current user is permitted access to the requested URL, based on the user name or the list of roles of which a user is a member.	System.Web.Security.UrlAuthorizationModule
UrlMappingsModule	Supports mapping a real URL to a more user-friendly URL.	System.Web.UrlMappingsModule
WindowsAuthentication	Sets the identity of the user for an ASP.NET application when Windows authentication is enabled.	System.Web.Security.WindowsAuthenticationModule

IIS 7 Request Processing

In IIS 7, the IIS and ASP.NET request pipelines combine to process requests with an integrated approach. The new request-processing architecture consists of an ordered list of native and managed modules that perform specific tasks in response to requests.
This design provides several benefits over previous versions of IIS. First, all file types can use features that were originally available only to managed code. For example, you can now use ASP.NET Forms authentication and Uniform Resource Locator (URL) authorization for static files, Active Server Pages (ASP) files, and all other file types in your sites and applications.
Second, this design eliminates the duplication of several features in IIS and ASP.NET. For example, when a client requests a managed file, the server calls the appropriate authentication module in the integrated pipeline to authenticate the client. In previous versions of IIS, this same request would go through an authentication process in both the IIS pipeline and in the ASP.NET pipeline.
Third, you can manage all of the modules in one location, instead of managing some features in IIS and some in the ASP.NET configuration. This simplifies the administration of sites and applications on the server.

IIS 7 Application Pools

Application pools separate applications by process boundaries to prevent an application from affecting another application on the server. In IIS 7, application pools continue to use IIS 6.0 worker process isolation mode. In addition, you can now specify a setting that determines how to process requests that involve managed resources: Integrated mode or Classic mode.
Note: In IIS 6.0, worker process isolation mode and IIS 5.0 isolation mode are set at the server level. This makes it impossible to run both isolation modes on the same server. However, in IIS 7, Integrated mode and Classic mode are set at the application pool level, which enables you to run applications simultaneously in application pools with different process modes on the same server.

Integrated application pool mode

When an application pool is in Integrated mode, you can take advantage of the integrated request-processing architecture of IIS and ASP.NET. When a worker process in an application pool receives a request, the request passes through an ordered list of events. Each event calls the necessary native and managed modules to process portions of the request and to generate the response.
There are several benefits to running application pools in Integrated mode. First the request-processing models of IIS and ASP.NET are integrated into a unified process model. This model eliminates steps that were previously duplicated in IIS and ASP.NET, such as authentication. Additionally, Integrated mode enables the availability of managed features to all content types.

Classic application pool mode

When an application pool is in Classic mode, IIS 7 handles requests in the same way as in IIS 6.0 worker process isolation mode. ASP.NET requests first go through native processing steps in IIS and are then routed to Aspnet_isapi.dll for processing of managed code in the managed runtime. Finally, the request is routed back through IIS to send the response.
This separation of the IIS and ASP.NET request-processing models results in duplication of some processing steps, such as authentication and authorization. Additionally, managed code features, such as Forms authentication, are only available to ASP.NET applications or applications for which you have script mapped all requests to be handled by aspnet_isapi.dll.
Be sure to test your existing applications for compatibility in Integrated mode before upgrading a production environment to IIS 7 and assigning applications to application pools in Integrated mode. You should only add an application to an application pool in Classic mode if the application fails to work in Integrated mode. For example, your application might rely on an authentication token passed from IIS to the managed runtime, and, due to the new architecture in IIS 7, the process breaks your application.

HTTP Request Processing in IIS 7

IIS 7 has a similar HTTP request-processing flow as IIS 6.0. The diagrams in this section provide an overview of an HTTP request in process.
The following list describes the request-processing flow that is shown in Figure 1:

When a client browser initiates an HTTP request for a resource on the Web server, HTTP.sys intercepts the request.
HTTP.sys contacts WAS to obtain information from the configuration store.
WAS requests configuration information from the configuration store, applicationHost.config.
The WWW Service receives configuration information, such as application pool and site configuration.
The WWW Service uses the configuration information to configure HTTP.sys.
WAS starts a worker process for the application pool to which the request was made.
The worker process processes the request and returns a response to HTTP.sys.
The client receives a response.

Figure 1: Overview of an HTTP Request
In a worker process, an HTTP request passes through several ordered steps, called events, in the Web Server Core. At each event, a native module processes part of the request, such as authenticating the user or adding information to the event log. If a request requires a managed module, the native ManagedEngine module creates an AppDomain, where the managed module can perform the necessary processing, such as authenticating a user with Forms authentication. When the request passes through all of the events in the Web Server Core, the response is returned to HTTP.sys. Figure 2, below, shows an HTTP request entering the worker process.

Figure 2: Detail of a HTTP request inside the Worker Process

Difference between Web Farm and Web Garden in IIS ?

2011-04-13T15:54:00.000+05:30

I have been asked this question many times by different readers of my blog. They wanted to know about the fundamentals of Web Farms and Web Garden . In this blog post I am going to explain the what is the exact difference between web farm and web garden, what are the advantages and disadvantages of using them. I have also described how to create web garden in different version of IIS.
Overview :
Visual Studio having its own integrated ASP.NET engine which is used to run the ASP.NET Web application from Visual Studio. ASP.NET Development Server is responsible for execute all the request and response from client. Now after the end of development, when you want to host the site on some server to allow other peoples to access, concept of web servers comes in between. A web server is responsible for provide the response for all the requests that are coming from clients. Below diagram showing the typical deployment structure of a ASP.NET Web application with a single IIS.

Clients request for resources and IIS Process the request and send back to clients. If you want to know more details on How IIS Process the request please read one of my article over “How IIS Process ASP.NET Request ?” .

Web Farm :

This is the case, where you have only one web server and multiple clients requesting for the resources from the same server. But when there is huge numbers of incoming traffic for your web sites, one standalone server is not sufficient to process the request. You may need to use multiple server to host the application and divide the traffic among them. This is called “Web Farm” . So when you are hosting your single web site on multiple web server over load balancer called “Web Farm”. Below diagram showing the over all representation of Web Farms.

In general web farm architecture, a single application is hosted on multiple IIS Server and those are connected with the VIP ( Virtual IP ) with Load Balancer. Load Balancer IP’s exposed to external worlds to access. So whenever some request will come to server from clients, it will first hit the Load Balancer, then based on the traffic on each server LB distributed the request to corresponding web server. These web server may share same DB server or may be they can use replicated server in the back end.
So, In a single statement, When we host a web application over multiple web server to distributed the load among them is called Web Farm.
Web Garden :
Now, let’s have a look, what is Web Garden ? Both the terms sounds same, but they are totally different with each other. Before starting with Web Garden, I hope you have fundamental idea of what is Application Pool and what is Worker Process. If you have already read the article “How IIS Process ASP.NET Request ?” article then I can expect that you have now good idea on both of them.
Just to recall, When we are talking about requesting processing with in IIS, Worker Process (w3wp.exe ) takes care all of these. Worker Process runs the ASP.Net application in IIS. All the ASP.Net functionality inside IIS runs under the scope of worker process. Worker Process is responsible for handling all kind of request, response, session data, cache data. Application Pool is the container of worker process. Application pools is used to separate sets of IIS worker processes and enables a better security, reliability, and availability for any web application.
Now, by default each and every Application pool contains a single worker process. Application which contains the multiple worker process called “Web Garden”. Below is the typical diagram for a web garden application.
In the above diagram you can see, on of the application containing the multiple worker process, which is now a web garden.
So, a Web application hosted on multiple server and access based on the load on servers is called Web Farms and When a single Application pool contain multiple Worker process is called web garden.
Create Web Garden in IIS 6 and IIS 7
Now, I am going to show how you can change the Number of Worker process In both IIS 6 and IIS 7. For IIS 6, Right Click on Application Pool > Properties > Goto Performance Tab.

In the “Performance Tab” Section you would have one option called “Web Garden” where worker process sets to “1”, you can set the number of worker process that you required.
For IIS 7, Right Click on Application Pool > Go To Advance Settings > In Process Model section, you will have “Maximum Worker Processes” . You can change it more than 1 to make it as web garden.

In the above image you can also check the definition of Web Garden also.
You can find one of my previous article on the basic of same over here
Advantages of Web Farm and Web Garden :
Now, let’s have a look in to the advantages of both the Web farms and Web Garden.
Advantages of Web Farm

It provides high availability. If any of the server in the farm goes down, Load balancer can redirects the requests to other servers.
Provides high performance response for client requests.
Provides Better scalability of the web application and reduce the failure of application.
Session and other resource can be stored in a centralized location to access by the all server.

Advantages of Web Garden:

provides better application availability by sharing request between multiple worker process.
Web garden use processor affinity where application can swapped out based on preference and tag setting.
Less consumption of physical space for web garden configuration.

How to manage session in Web Farm Mode ?
While using session, requests are distributed among different servers. By default session mode is set to In Proc where session data stored inside worker process memory. But, In Web farm mode we can share the session among all the server using a single session store location my making it Out proc (State Server or SQL Server Mode). So, if some of the server goes down and request transferred to the other server by the Load balancer session data should be available for that request.
In the above diagram, you can see we can both the IIS server sharing the same session data which is stored in out of worker process. You can read one of my previous article “Exploring Session in ASP.NET” where I have explained how you can configure session mode for Out Process mode.
How to manage session in Web Garden Mode ?
When we are using Web garden where request is being taking care by different worker process we have to make the session mode as out process session mode as described earlier. For Web Garden we have configure the out process with in same server but for different worker process.

While using Web garden with your application you need do couple of configuration settings in web.config in <process Model> section where you need to set certain properties like cpuMask, RequestLimit, webGarden, ClientConnectCheck etc.
Summary : When we host a web application over multiple web server to distributed the load among them is called Web Farm and when One application having multiple worker worker process called Web garden.
In this blog post I have explained the very basics of what Web Farm is and what Web Garden is. As this blog post contains the basic information to understand the fundamentals of web farms and web garden concept, I will be posting a separate article with details configuration setting for web garden and web farm. You can read those below articles for more information
Boosting performance using an IIS web garden
How-To Configure Session State in a Windows Web Farm.
Role of Web gardens and web farms in ASP.NET
Hope this will help you.

How To Identify The Worker Process (w3wp.exe) For Debugging an ASP.NET application

2011-04-13T15:51:00.000+05:30

If you are debugging a ASP.NET web application which is hosted on IIS, you need to attach the particular worker process in Visual Studio to start debugging. To Attach a process we can go to Tools > Attach Process or use shortcut key Ctrl +P. The process window will show the worker process (w3wp.exe) which is currently running on IIS. You need to select the process and click on attach button to start the debugging.
Problem starts when you have multiple worker process running on IIS. If you have multiple sites hosted on IIS and each site having their own application pool then you will see the list of all worker process in the Process Attach window.

Here you need to identify the particular worker process which is associated with your application pool.
Note: Whenever we create a new Application Pool, the ID of the Application Pool is being generated and it’s registered with the HTTP.SYS (Kernel Level of IIS) . So whenever HTTP.SYS Received the request from any web application, it checks for the Application Pool and based on the application pool it send the request
To know more about IIS Request Process, here is one of my aticle How IIS Process ASP.NET Request
Identify Worker Process in IIS 6.0

• Start > Run > Cmd
• Go To Windows > System32
• Run cscript iisapp.vbs
• You will get the list of Running Worker ProcessID and the Application Pool Name.

So, here is your list of all worker process with corresponding application pool name. From the Application pool name you can easily identify which worker process is related with your application.
Identify Worker Process in IIS 7.0

From IIS 7.0 you need you to run IIS Command Tool ( appcmd ) .
• Start > Run > Cmd
• Go To Windows > System32 > Inetsrv
• Run appcmd list wp
This will show you list worker process that is running on IIS 7.0 in the similar format of IIS 6.0

How IIS Process ASP.NET Request

2011-04-13T15:41:00.002+05:30

Introduction

When request come from client to the server a lot of operation is performed before sending response to the client. This is all about how IIS Process the request. Here I am not going to describe the Page Life Cycle and there events, this article is all about the operation of IIS Level. Before we start with the actual details, let’s start from the beginning so that each and everyone understand it’s details easily. Please provide your valuable feedback and suggestion to improve this article.

What is Web Server ?

When we run our ASP.NET Web Application from visual studio IDE, VS Integrated ASP.NET Engine is responsible to execute all kind of asp.net requests and responses. The process name is "WebDev.WebServer.Exe" which actually takw care of all request and response of an web application which is running from Visual Studio IDE.
Now, the name “Web Server” comes into picture when we want to host the application on a centralized location and wanted to access from many locations. Web server is responsible for handle all the requests that are coming from clients, process them and provide the responses.

What is IIS ?

IIS (Internet Information Server) is one of the most powerful web servers from Microsoft that is used to host your ASP.NET Web application. IIS has it’s own ASP.NET Process Engine to handle the ASP.NET request. So, when a request comes from client to server, IIS takes that request and process it and send response back to clients.

Request Processing :

Hope, till now it’s clear to you that what is Web server and IIS is and what is the use of them. Now let’s have a look how they do things internally. Before we move ahead, you have to know about two main concepts
1. Worker Process
2. Application Pool

Worker Process: Worker Process (w3wp.exe) runs the ASP.Net application in IIS. This process is responsible to manage all the request and response that are coming from client system. All the ASP.Net functionality runs under the scope of worker process. When a request comes to the server from a client worker process is responsible to generate the request and response. In a single word we can say worker process is the heart of ASP.NET Web Application which runs on IIS.
Application Pool: Application pool is the container of worker process. Application pools is used to separate sets of IIS worker processes that share the same configuration. Application pools enables a better security, reliability, and availability for any web application. The worker process serves as the process boundary that separates each application pool so that when one worker process or application is having an issue or recycles, other applications or worker processes are not affected. This makes sure that a particular web application doesn’t not impact other web application as they they are configured into different application pools.

Application Pool with multiple worker process is called “Web Garden”.
Now, I have covered all the basic stuff like Web server, Application Pool, Worker process. Now let’s have look how IIS process the request when a new request comes up from client.
If we look into the IIS 6.0 Architecture, we can divided them into Two Layer

1. Kernel Mode
2. User Mode

Now, Kernel mode is introduced with IIS 6.0, which contains the HTTP.SYS. So whenever a request comes from Client to Server, it will hit HTTP.SYS First.

Now, HTTP.SYS is Responsible for pass the request to particular Application pool. Now here is one question, How HTTP.SYS comes to know where to send the request? This is not a random pickup. Whenever we creates a new Application Pool, the ID of the Application Pool is being generated and it’s registered with the HTTP.SYS. So whenever HTTP.SYS Received the request from any web application, it checks for the Application Pool and based on the application pool it send the request.

So, this was the first steps of IIS Request Processing.
Till now, Client Requested for some information and request came to the Kernel level of IIS means at HTTP.SYS. HTTP.SYS has been identified the name of the application pool where to send. Now, let’s see how this request moves from HTTP.SYS to Application Pool.
In User Level of IIS, we have Web Admin Services (WAS) which takes the request from HTTP.SYS and pass it to the respective application pool.

When Application pool receive the request, it simply pass the request to worker process (w3wp.exe) . The worker process “w3wp.exe” looks up the URL of the request in order to load the correct ISAPI extension. ISAPI extensions are the IIS way to handle requests for different resources. Once ASP.NET is installed, it installs its own ISAPI extension (aspnet_isapi.dll) and adds the mapping into IIS.
Note : Sometimes if we install IIS after installing asp.net, we need to register the extension with IIS using aspnet_regiis command.

When Worker process loads the aspnet_isapi.dll, it start an HTTPRuntime, which is the entry point of an application. HTTPRuntime is a class which calls the ProcessRequest method to start Processing.

When this methods called, a new instance of HTTPContext is been created. Which is accessible using HTTPContext.Current Properties. This object still remains alive during life time of object request. Using HttpContext.Current we can access some other objects like Request, Response, Session etc.

After that HttpRuntime load an HttpApplication object with the help of HttpApplicationFactory class.. Each and every request should pass through the corresponding HTTPModule to reach to HTTPHandler, this list of module are configured by the HTTPApplication.
Now, the concept comes called “HTTPPipeline”. It is called a pipeline because it contains a set of HttpModules ( For Both Web.config and Machine.config level) that intercept the request on its way to the HttpHandler. HTTPModules are classes that have access to the incoming request. We can also create our own HTTPModule if we need to handle anything during upcoming request and response.

HTTP Handlers are the endpoints in the HTTP pipeline. All request that are passing through the HTTPModule should reached to HTTPHandler. Then HTTP Handler generates the output for the requested resource. So, when we requesting for any aspx web pages, it returns the corresponding HTML output.
All the request now passes from httpModule to respective HTTPHandler then method and the ASP.NET Page life cycle starts. This ends the IIS Request processing and start the ASP.NET Page Lifecycle.

Conclusion

When client request for some information from a web server, request first reaches to HTTP.SYS of IIS. HTTP.SYS then send the request to respective Application Pool. Application Pool then forward the request to worker process to load the ISAPI Extension which will create an HTTPRuntime Object to Process the request via HTTPModule and HTTPHanlder. After that the ASP.NET Page LifeCycle events starts.
This was just overview of IIS Request Processing to let Beginner’s know how the request get processed in backend. If you want to learn in details please check the link for Reference and further Study section.

Reference and Further Study

A low-level Look at the ASP.NET Architecture
IIS Architecture

Troubleshooting: Could not start the IIS Admin Service on Local Computer

2011-02-09T17:59:00.001+05:30

Q.) When I try to start the IIS Admin Service from services.msc I receive the following error:

Could not start the IIS Admin Service on Local Computer
Error2: The system cannot find the file specified.

At the same time I can also see the following message in the System event log:

Error: The IIS Admin service terminated with the following error. The system cannot find the file specified

Source Name: Service Control Manager

Event ID: 7023

Ans.)This error usually occurs when the MetaBase.xml file is either missing or has been corrupted. MetaBase.xml is the file wherein the IIS 6 configurations are written to and read from.

The default location for MetaBase.xml is C:\WINDOWS\system32\inetsrv\ . The default location for MetaBase.xml file back up is C:\WINDOWS\system32\inetsrv\History\

To solve this problem you can either restore the copy of the MetaBase.xml file (If you have a separate backup) or grab a copy from the History folder and place it in the C:\WINDOWS\system32\inetsrv\ folder. After which rename it to MetaBase.xml. Rename it to MetaBase.xml? Yeah! That's because in the History folder you will find the backup in the form MetaBase_0000000244_0000000000.xml . Subsequently, you will also find backups of the MBSchema.xml in the same format.

The MetaBase.xml file is backed up whenever you make any configurational changes to websites, application pools or any IIS related settings. By default, C:\WINDOWS\system32\inetsrv\History\ contains 10 most recent backups. However, this property itself can be changed from MetaBase.xml. Here's how to do it,

Open up Metabase.xml file in your favorite text editor. Now look for the section that says IIsComputer. In this section you will find an entry which says, "MaxHistoryFiles". By default, the value of this property is set to 10. You can change that value to whatever you want. Save the changes and start the IIS Admin Service.

All said, this is not the recommended way of changing the MetaBase.xml file :) Do not change the Metabase.xml file directly until you are very certain of what you are doing. But, if not this way then how? Very simple, just run the following command from the command prompt:

cscript.exe adsutil.vbs set /MaxHistoryFiles "12"

As you can notice I am changing the value of the maximum history file to 12. You can place any number there that you want. Now here's something interesting! There may be cases where in you will open the MetaBase.xml file after running the above command and do not see your change reflected. The changes only reflected after you restart the IIS Admin Service. Well that's because you do not have Enable Direct MetaBase Edit check box selected in the IIS properties. To see the changes take effect instantaneously run this command from the command prompt:

cscript.exe adsutil.vbs set /EnableEditWhileRunning "1"

Note: Sometimes after you restart the IIS admin service, the websites are in stopped state and you will have to start them manually to get going.

Update 21/08/2008: I wouldn't want you to enable Direct Metabase Edit for this scenario, as I figured out that when you use Adsutil.vbs the changes are made into the IN-MEMORY metabase.They will be reflected instantaneously in your environment and will then be written to the physical Metabase.xml after 2 mins.

Now you are all set to reflect changes as soon as they are made. However never do this on a production box. This was shown for instructional purposes so that we move along quickly. :) To de-select the Enable Direct MetaBase Edit check box run this command

cscript.exe adsutil.vbs set /EnableEditWhileRunning "0"

Problem solved and we also know a little about MetaBase.xml file now. Let me know if you have any issues!

I will soon be coming out with posts on IIS command line utilities and Metabase.xml

Web Server Clustering

2010-05-14T19:49:00.002+05:30

Microsoft Internet Information Server

Abstract

This white paper is an overview of clustering technologies as they relate to Web servers, specifically Microsoft® Internet Information Server (IIS), Windows Clustering, Microsoft Windows® 2000 Advanced Server Network Load Balancing (NLB), Microsoft Windows NT® Load Balancing Service (WLBS), and other industry standards as they are defined by their associated Request for Comments (RFC) documents.

This white paper describes different techniques for implementing your highly available Internet presence.

This white paper assumes that you are familiar with Microsoft Windows NT Server 4.0, Microsoft Windows 2000 Server, Microsoft Windows 2000 Advanced Server, Microsoft Windows 2000 Datacenter Server, Internet Information Server, Transmission Control Protocol/Internet Protocol (TCP/IP), and Domain Name System (DNS). You should also be familiar with the World Wide Web Consortium (W3C) and Request for Comments (RFC).

Description of a Server Cluster

A server cluster is a group of independent servers that are managed as a single system for higher availability, easier manageability, and greater scalability.

In a Web server environment, server clusters can be defined in two basic ways:

Active/Active
- There are multiple independent, redundant servers
- The load is distributed through round-robin DNS
- The load is balanced by a load-balancing solution (for example, WLBS)
Active/Passive
- Multiple servers are configured to provide a service
- Only a single server provides the service at any given time
- Other servers serve as hot-spares in case of a server (service) problem

Active/Active Solutions

Round-Robin DNS—RFC 1794

Round-robin DNS is a method for managing server congestion by distributing requests between multiple servers.

By using the round-robin DNS method, multiple DNS 'A' records are created for the Fully Qualified Domain Name (FQDN) that the client is trying to access. Each 'A' record lists the FQDN and the individual IP address for each node in the Web farm. Each client request resolves to a different IP address (based on the number of 'A' records). This allows incoming requests to be mapped to different servers in the Web farm.

Round-robin is not typically considered load balancing. Load balancing distributes connection loads across multiple servers, giving preference to those servers with the least amount of congestion. By using the round-robin method, server distribution remains on a rotating basis, one IP address to one user, with no regard to server congestion. DNS simply responds with the next 'A' record in the entry for that FQDN.

Round-robin DNS provides no fault tolerance or fault detection. That is, if a server stops working, DNS continues to distribute that server's IP address.

Load Balancing

A load balancer processes requests and relays them to server address clusters. A server address cluster has the following properties:

Has an FQDN in the domain namespace (for example, www.microsoft.com)
Has a pool of valid IP addresses to computers that can fulfill the requested service that is associated with the FQDN. That is, if the FQDN is to provide Web services, each IP address must correspond to an HTTP server (for example, Internet Information Server). These IP addresses can be valid IP addresses that are assigned by Internet Assigned Numbers Authority to you, or they can be IP addresses in the private address space as defined by RFC 1918: Address Allocation for Private Internets. For example:
- Class A (10.0.0.0 through 10.255.255.255)
- Class B (172.16.0.0 through 172.31.255.255)
- Class C (192.168.0.0 through 192.168.255.255)
Uses a load specification from a list of predetermined load formulas. (For specific details, see the documentation for your load-balancing solution.)

Optional features to be provided by the specific solution include:

A TCP port that is designated to test for a server heartbeat. These tests only verify that the server is responding on the TCP level. For example, a server heartbeat for Internet Information Server (IIS) can perform an HTTP trace request (RFC 2069, Section 9.8), which checks to verify if the programs that are requested (in this case, HTTP services) are available on the requested server.
A specification for a fail-over server in the event that all computers become unavailable.
A balance interval to determine how much time to wait between balance cycles.

Windows NT Load Balancing Service and Windows 2000 Network Load Balancing

Windows NT Load Balancing Service (WLBS), a component of Windows NT Server 4.0, Enterprise Edition, allows for the balancing of many TCP or IP-based services, including, but not limited to, WWW and FTP. This runs on a single Windows NT Server 4.0-based computer, and balances the request between any number of individual servers that provide a TCP or IP service.

For additional information about WLBS, see the following Web site:

http://www.microsoft.com/technet/archive/winntas/deploy/depovg/wlbsdepl.mspx

For Windows 2000, load balancing is implemented in Windows 2000 Advanced Server as Network Load Balancing (NLB).

Active/Passive Solution

Windows NT Server 4.0 supports two-node clustering through Microsoft Cluster Server (MSCS), which is included as a component of Windows NT Server 4.0, Enterprise Edition. Additional information about MSCS is available in the MSCS FAQ, which is located at:

http://www.microsoft.com/ntserver/support/faqs/clustering_faq.asp

Windows 2000 Advanced Server supports two-node clustering. Clustering information for Windows 2000 Advanced Server is available at:

http://www.microsoft.com/business/default.mspx

Microsoft Windows 2000 Datacenter Server supports four-node clustering. Windows 2000 Datacenter Server information is available on the following Web site:

http://www.microsoft.com/windows2000/datacenter/

A node is defined as a single installation of Windows NT Server 4.0, Enterprise Edition, on a server that has the following characteristics:

Has local hardware (RAM, CPU, local boot, and system partitions for Windows NT)
Has a network connection that enables it to communicate with an additional node
Has a means to share a disk resource (for example, shared SCSI or Fibre Channel)

Top of page

Internet Information Server on MSCS

IIS is designed as a high performance, highly scalable, highly extensible way to provide Web content. Depending on your definition of Web content, your recommended solution may be different. If you want to enlist static HTML with client-side scripting, or static content available to FTP users, you can use IIS as a standalone server to meet your needs. If you want to use IIS as a basis for Web programs, including ASP pages (or other server-side scripting), server-side COM objects, Microsoft Site Server, or Microsoft Commerce Server, and you want multiple redundant servers to meet the need for high availability, WLBS with multiple individual Web servers can help you to meet your goals.

For information about installing IIS on MSCS, see the white paper located at:

http://www.microsoft.com/ntserver/techresources/deployment/enterprise/ntoption.asp

This white paper contains instructions on how to install and configure the WWW and FTP services for failover between two nodes.

Having these services (and other services) on the cluster provides high availability for those resources.

In this white paper, resources are defined as basic system components that provide a service to clients in a client or server environment. These services can move freely from one node in the cluster to the other, but can only be online on one node at a time.

In its simplest form, an IIS server is basically the following five resources:

An IP address
A network name
A Disk resource
An IIS server instance
A Microsoft Distributed Transaction Coordinator (MSDTC)

These resources are maintained in a virtual state and owned by the active (owning) node of the cluster. They are virtual, in that they are reliant on the Cluster service and their individual resource DLLs, rather than an actual installation of Windows NT Server 4.0, Enterprise Edition.

Content is maintained on the shared disk resource, so that it remains available in the event that a node becomes unavailable.

Connections to resources are made through the virtual IP addresses. Therefore, the FQDN in DNS points to the IP address resource to which you have bound your IIS server instance.

Microsoft Cluster Server provides an ideal environment for backend applications such as Microsoft SQL Server or Microsoft Exchange Server. However, MSCS is not ideal for IIS and a highly available Web presence. WLBS is more suited to the requirements of that environment.

IIS and MSCS Implementation

The SMTP and NNTP services in Microsoft Windows NT Option Pack on Windows NT Server 4.0 are not cluster-aware. That is, although you can install them, they do not fail over because they do not have a resource DLL. If you require e-mail and news services in a clustered environment, use Exchange Server. For additional information, see the following Web page:

http://www.microsoft.com/ntserver/partners/findoffering/serversolutions/exchange.asp?bPrint=True

Windows 2000 Advanced Server provides a resource DLL for the SMTP and NNTP services. Therefore, these services are cluster-aware in Windows 2000.

Microsoft Outlook® Web Access is not supported on a cluster.

For additional information about other Exchange Server components that are not supported in a cluster environment, see the Docs\Word_Docs\Clustering\Cluster.doc file on the Exchange Server 5.5 CD.

ASP pages (and other server-side scripting) work in a cluster environment; however, because you must implement these as server-side COM objects that must exist and be registered on each node, their extensibility is limited. If you require Active Server Pages (ASP) in the Web server environment, use WLBS.

Microsoft FrontPage® Server Extensions and Microsoft Index Server are not supported on MSCS.

Site Server is not supported on MSCS. For additional information, see the following article in the Microsoft Knowledge Base:

228999: Site Server 3.0 Services Cannot Be Configured to Work with MSCS

Active/Passive is the only way to use IIS on MSCS.

Windows NT Load Balancing Service

Load balancing in a Web farm is the preferred method for creating a highly available Web presence.

Windows Load Balancing Service (WLBS) is a software-based load-balancing solution that is installed as a virtual Network Adapter driver that filters traffic to the physical adapter to which it is bound. At this layer, it distributes the requests based on the driver setup. This allows a client's requests to be passed unchanged to the server that can fulfill the client's request.

WLBS provides the ability to assign client affinity to requests. This allows sessions to be maintained between client requests. This is in contrast to the round-robin DNS method in which every incoming request is sent to the next 'A' record in the DNS servers.

The following list of resources provides information about the differences between using IIS on a cluster and WLBS for your high-availability Web site.

For a Web environment, the concept of a Web server cluster is best described in the following article:
http://www.microsoft.com/technet/prodtechnol/windows2000serv/technologies/iis/deploy/confeat/webclust.mspx
The following links contain a feature overview and a technical overview of WLBS:
http://www.microsoft.com/ntserver/ProductInfo/features/WlbsFeat.asp
http://www.microsoft.com/ntserver/ProductInfo/Enterprise/Wlbs.asp
For Web farm content, there is no single disk resource for maintenance of your content, unless you point to a single file share; however, pointing to a single file share would likely create a network bottleneck. Therefore, content (and metadata) must be replicated between servers. You can accomplish this by using Site Server Content Replication and metabase deployment.
Because of the nature of a Web farm (each server is independent of the other), the nodes in a Web farm do not communicate with one another to ensure responsiveness (as the heartbeat does in MSCS). WLBS automatically detects and removes unresponsive servers.
The Microsoft Internet Information Server Resource Kit contains a utility (HTTPMon) that provides a graphical (Web-based) interface from which to monitor the servers in your Web farm.

Maintaining Session State in Web Server Clusters

HTTP (HTTP/1.1—RFC 2068) is a stateless (and connectionless) protocol. Therefore, to a Web server, each HTTP request is separate and unrelated to all other requests. There must be a way for the page to identify one user request from another outside of the protocol that is being used to make the request. Cookies are used for this.

You can use cookies (HTTP State Management Mechanism—RFC 2616) in a Web farm through the ASP request and Response objects (and through other means). However, cookies are stored on the client, and are limited to 4,096 bytes.

To overcome some of the shortcomings of cookies, session-aware load balancing through software or hardware is possible.

You can accomplish session management while using round-robin DNS by using software in the form of IIS and ASP (a Session object), and the Session_OnStart event when used in a Web program's Global.asa file.

The following article contains additional information about the management of sessions through ASP pages:

http://msdn.microsoft.com/workshop/server/asp/active.asp

Another software-based session-management mechanism is instituted through Site Server Personalization, which uses a database server (SQL) that houses a User Property database that is a backend server that is available to all Web servers in the Web farm. For additional information, see the following Web site:

http://www.microsoft.com/siteserver/default.htm

For additional information about using Site Server to manage your sessions, see the following Web site:

http://msdn.microsoft.com/workshop/server/nextgen/sessiondata.asp

Hardware-based session management is controlled through session-distribution algorithms that are built into the hardware load-balancing solution. These algorithms map to servers in the Web farm based on an examination of the packet for the client IP address, port, and so on. This is done without modification to the packet. For example, in WLBS, this is controlled through affinity. For basic load balancing, you must set the Affinity setting to None; to maintain state, choose Single of Class C. On Local Director from Cisco Systems, Inc., use the Sticky setting to maintain this.

Take Your ASP.NET 2.0 App Offline

2010-05-14T13:06:00.005+05:30

I just learned this a few minutes ago, but you can take an ASP.NET 2.0 application offline temporarily by uploading a file called App_Offline.htm. It will spin down the appdomain and redirect all requests to that page. Cool o !

Basically, if you place a file with this name in the root of a web application directory, ASP.NET 2.0 will shut-down the application, unload the application domain from the server, and stop processing any new incoming requests for that application. ASP.NET will also then respond to all requests for dynamic pages in the application by sending back the content of the app_offline.htm file (for example: you might want to have a “site under construction” or “down for maintenance” message)

This provides a convenient way to take down your application while you are making big changes or copying in lots of new page functionality (and you want to avoid the annoying problem of people hitting and activating your site in the middle of a content update). It can also be a useful way to immediately unlock and unload a SQL Express or Access database whose .mdf or .mdb data files are residing in the /app_data directory.

Once you remove the app_offline.htm file, the next request into the application will cause ASP.NET to load the application and app-domain again, and life will continue along as normal.
Hope this helps,

On Web Gardens, ASP.NET, and IIS 6.0

2010-05-14T12:57:00.000+05:30

So as I’ve been working with a Web site deployed using Web gardens over the past two years, I’ve learned some painful quirks that come along with them.

What is a Web garden?

Think of a web garden as a web farm, but all in the context of a single machine. You have multiple worker processes running your application, preferably each running on a different core in your multicore computer.

Available right-clicking an application pool and choosing Properties in the IIS Management snap-in.

Why is this a good thing? Is it for performance? Well, not performance alone and not necessarily at all. Using a Web garden will only be good for performance if your application does some unusual blocking and locking while processing a request such that all the little threads within an individual worker process get tied up waiting for another thread to release the lock. We had this for a while because our Web framework had a nasty threading bug when rendering templates, and running in a Web garden helped because while separate threads within a single process could clobber one another, separate threads in separate processes obviously couldn’t.

The bigger gain for Web gardens is not performance but robustness. If one of the worker processes hosting your application goes ape in that you get stuck in a loop and run at full tilt CPU until health monitoring kills you, then you’ve just stopped serving all requests from that process until it’s killed. If that’s the only process, then you’ve stopped serving requests for your Web site entirely. But if you have a Web garden with, say, 3 worker processes and one of them goes AWOL, then at least you’re serving requests from the remaining 2 until the bananas worker process is shut down and spun up again.

What are the caveats?

There are several caveats to consider, but they’re all important from a scalability perspective. In fact, enabling Web gardening can be a good way to see if your application will be able to function in a Web farm scenario on multiple servers reasonably well. If you can deal with a Web garden now, you’ll have a far easier time scaling out to multiple servers in the future than if you’d stuck with an application that assumes everything lives within the same worker process.

No `InProc` session storage

One of the caveats about using a Web garden is that if you’re using session state in your application, then you need to use an out-of-process session state, such as the ASP.NET State Service or sessions stored in SQL Server. InProc session management won’t work because each worker process will be maintaining its own session state. So if a customer is browsing your Web site and you have 3 worker processors, then your customer has a 1 in 3 chance of losing his session state as IIS round-robins his subsequent requests among the 3 available worker processes. If you use an out-of-process session state, then you can be sure that all 3 worker processes are consulting the same single resource as the place to store and retrieve session data.

With InProc storage and Web gardens, Bob the Blue Dot only has a 1 in 3 chance of finding his original session on any given request.

No built-in caching mechanism

Similarly, if you’re using System.Web.Caching, you need to remember that each individual worker process is going to maintain its own cache. So if you cache a big list of products on your catalog listing page and you have three worker processes, then the database is going to get hit at least three times and that page is going to get cached in three separate places in RAM–one place for each process. This can make an operation such as clearing the cache difficult.

Suppose you have a protected HTTP handler, say, ClearCaches.axd, which if pinged by some administrative IP address tells the System.Web.Caching cache to clear itself. You’ll only have cleared out the cache for the worker process that happened to serve that particular request. To clear them all, you’d have to recycle all of the worker processes through the IIS Management snap-in or just keep pinging yourClearCaches.axd until you were confident that IIS had round-robined you across to all of the worker processes. Neither is really ideal.

A better solution would be to move to an out-of-process cache like memcached. Then you only have one service that you need to clear the cache for, and that cache clearing action will be observed by all three worker processes.

These are the two things that you’d naturally expect to have to deal with when running Web gardens. Now let’s talk about two that you normally wouldn’t expect. (That’s a nice way of saying that I learned them the hard way.)

Poor `App_Offline.htm` integration

So ASP.NET 2.0 has this little nifty feature that revolves around a file calledApp_Offline.htm. You dump a file named like this in the root of your ASP.NET Web application. Upon the next request to any page on the site served through the ASP.NET ISAPI handler, the worker process will spin down, and the contents of theApp_Offline.htm file will be served instead. (Stupidly, ASP.NET will send a 404 header for this, which is plain wrong, but this is hard-coded.) This unlocks the DLLs in your site’s bin directory. So if you filled that file with a message like “We’re down for maintenance; check back soon,” you’d be able to xcopy over the new binaries to the bin directory, delete the App_Offline.htm file when you’re done, and you’d have provided a simple and graceful site maintenance message to your users in the process.

But this doesn’t work well for Web gardens. The problem is that the worker process spins down and releases its lock on your application binaries only after the next request to that individual process after you created the App_Offline.htm file. So if I have a Web garden with 3 worker processes A, B, and C, and I plunk myApp_Offline.htm file down, and I visit the home page of my site, then something like this might happen: Worker process B decides to process my request, notes that theApp_Offline.htm file exists, serves me the contents of the file, and then spins down and releases its lock on the application binaries. But processes A and C are still churning along and locking those files. I’d either have to refresh the homepage a whole bunch of times to be sure I had round-robined across all of the binaries to get them to all spin down (less than ideal), or I’d have to kill all the worker processes by stopping the application pool in the IIS Management snap-in. In the end, though, it’s easiest to just pretend this feature doesn’t exist for you and find some alternative update mechanism, such as deactivating your main site and activating a completely separate Web site in IIS that simply displays the site maintenance message.

Bug in .NET Framework installer can cause a strange scenario

I lost some hair over this one because it’s unexpected and only appears under a very specific scenario. Here we go:

Take a server running .NET 3.0 and an ASP.NET Web site running in an application pool that has Web gardens enabled (number of processes: 3). The web.config configuration is something like the following:


      cookieless="UseCookies"
      cookieName=".authz"
      mode="StateServer"
      regenerateExpiredSessionId="true"
      stateConnectionString="tcpip=127.0.0.1:42424"
      timeout="60"
      useHostingIdentity="true" />

Now upgrade the machine to .NET 3.5 SP1. Reboot the server. Stand back in shock and horror to find that sessions are no longer maintained across the worker processes, as if all of them have reverted to InProc session storage. You see that the configuration obviously still says StateServer, but it Simply Does Not Work. You quickly reduce to 1 worker process as the current workaround.

The problem appears to occur when all of the following conditions are true:

You are running Windows Server 2003 (IIS 6.0) and an ASP.NET 2.0 web site.
The Web site is configured to use Web Gardens, where the maximum number of worker processes is greater than 1. Because of this, you have configured your application to use an out-of-process session storage; in this scenario, the ASP.NET State Service running on the local machine.
The application pool identity is set not to NETWORK SERVICE but to a custom, low-privileged user account that you created per a deployment best practice.
You run an installer that updates the .NET framework; in my case, this was an update from .NET 3.0 to .NET 3.5 SP1.
When the upgrade finishes and you reboot the server, you find that your session variables are frequently lost upon refreshing a page, since there is only a 1 in 3 chance of you getting the original worker process that served your original request. But this shouldn’t matter, since you’re using the ASP.NET state service. What broke?

When using the ASP.NET state service, ASP.NET uses a value called themachineKey to encrypt and/or hash all session data to be stored (I don’t know if it’s encrypting or hashing or both, but it’s not an important distinction for this discussion). This is so that when any worker process asks for data from the service using a session identifier, it can be sure that the data was not tampered with while it was being stored in the external data source.

If you are on a web farm, then you probably have a static machineKey defined in yourweb.config file, and this issue does not occur. But for a single-server web garden scenario, you probably rely on the default machineKey setting, which is set toAutoGenerate,IsolateApps for ASP.NET 2.0 applications. This means that ASP.NET automatically generates a machine key that is unique to your application pool. It regenerates this key according to some algorithm, but that is not important for this discussion.

The generated value is normally stored in the registry underHKLMSOFTWAREMicrosoftASP.NET2.0.50727.0AutoGenKeys{SID of the Application Pool Identity}. But the .NET Framework installer incorrectly (I do believe this is a bug) destroys this registry key and, to add insult to injury, resets the permissions on this key such that your custom application pool identity cannot write to the registry entry when it goes to create its new machine key.

Without being able to store this key, each process will think session data inserted by other processes has been tampered with or is otherwise invalid. Yikes!

The result is that each worker process that spins up in the web garden is using its own in-memory copy of a machine key that it generated just in time, effectively creating a web farm scenario by accident. For example, worker process A spins up, sees that no AutoGenKey entry exists (indeed, it cannot even read it), generates its own and begins using that to hash data sent to the ASP.NET State Service. It tries to save this new machine key to the registry entry, but fails silently. Worker process B spins up, sees that no AutoGenKey entry exists, generates its own and begins using that to hash data…you see where this is going.

Bad permissions on this one registry key can cause some real headache-inducing behavior as everything seems to behave as if it were InProc.

The result is now you have session data hashed with three different machine keys. Though the data for the session identifier exists, two out of three of the worker processes will reject it as invalid/tampered because it is using its own key.

You could get around this by explicitly setting a custom machineKey in your web.config file.

Or you could re-run aspnet_regiis.exe -ga MachineNameApplicationPoolUserName at a Command Prompt to fix up the broken permissions.

Conclusions and Delusions

There you have it! Web gardens are a really neat feature for increasing the robustness of your application as well as testing the general suitability of your application for migration to a Web farm scenario. But documentation out there is pretty scarce, and I get the feeling that people don’t use Web gardens all that often. Hopefully, these little issues that I’ve run across will save somebody some heartache in the future. Good luck!

Thanks to : http://nicholas.piasecki.name/blog/2009/02/on-web-gardens-aspnet-and-iis-60/

Exit USA - Travel Back to home country

2010-04-30T00:28:00.002+05:30

Home > Immigration > Visitor visa> US-Visit Exit

Exit USA - Travel Back to home country

Once your legal stay is over you should leave USA. Leaving usa in timely and allowed manner is legally required and also helpful in all your future entries into USA. Do some preparation before getting ready to leave the US.

Make a couple of photocopies of your I-94 and passport/visa and keep them safely. Keeping a copy in your hand baggage is always useful. These duplicate documents are useful in case you lose your passport etc. If you are a visiting parent/relative it's a good idea to give a copy to your son/daughter. These documents may also be useful for your future visits to the US.
Check with the airlines for luggage weight limits and prepare your luggage accordingly. It is always better to be informed and save yourself time and frustration, since the airlines do not allow excess weight and you may have to pay extra dollars for exceeding the limit..
If you are carrying any gifts, make sure you are aware of the custom rules of your country, so that you don't have to face any issues at customs in your country. Below is some information about customs regulations in India.
At the day of departure, reach the airport at least 2hrs before departure time, since you need some time for checking etc.

Once you reach the airport :
Look for your airline checking counter.
Following are few important things you must do and are required by the US immigration law.

Handover your I-94 to the airline staff at the airline checking counter. When you do so, make sure that the airline person has taken out the I-94 stub. If they have not taken it out, ask them to do so.

Note : Effective May 6, 2007, international visitors will no longer be required to use the US-VISIT exit when they leave the United States. International visitors who received a U.S. Customs and Border Protection (CBP) Form I-94, Arrival-Departure Record, upon arrival must still return the form to an airline or ship representative when departing the United States.

Once you reach your destination/home country.

You may have to go through the immigration check counter.
You may be required to fill some customs and immigration clearance forms for your country.

For Indian citizens, on going back to India, you will have to fill a forms called Arrival or Disembarkation form.

Related Topics :

First Air Travel To USA- Plan a hassle free trip

2010-04-30T00:26:00.002+05:30

First Air Travel - Plan a hassle free trip

Travelling can be exiting or exhausting depending on the amount of homework you do before you actually board the plane. Here are some useful travel trips.

Tips prior traveling:

What to Do?

Choose the flight best suited to you.
Try to get the best deal on your tickets. Find out the rates offered by other airlines.
Booking tickets through a travel agent is always better. Agents may give you some discount.
When you book your ticket, mention your food preference whether you want Vegetarian or Non vegetarian food.
Make sure the date and time of travel on your ticket is correct. Call up the local airlines office to confirm. Flight timings may confuse you (e.g. Boarding on 5/1/2000 at 00:45 means 4th night 12:45 PM and not 5th night, as many airlines start with 00:00 after midnight.)
You should also confirm about the luggage limit that you can carry (the weight and number of bags for both cabin and check in luggage).
Make sure that you have reached to the right terminal, for your airlines departure.
Try to reach the airport at least 3 hours before departure. This way you can get your seat preferences. Different airlines have different seating arrangements e.g.3-3-3, 3-4-3, 2-2-2 etc.
Each of your luggages should have your name and address tag. Your luggage has to be identified at the destination airport. Naming is also helpful in case you lose your luggage.
Get currency of the destination country. You can exchange currency from the authorized banks e.g. State Bank Of India, etc. or from organizations like Thomas cook etc. Normally they have counters at the airport too. They also make an entry on your passport.

How to manage your luggage?

1. Hand or cabin luggage: This is what you can carry with you in the plane. Keep it small and handy, so that you can keep it in the overhead luggage space in the cabin. Trolley bags are always advisable. Many airlines allow one cabin bag, but ladies can carry their purse or handbag along with their cabin bag. Total linear dimensions (length+height+width) of each cabin baggage must not exceed 112cms (45 inches), and weight must not exceed 14 to 20kgs (30-40 pounds).

2. Check in luggage: These are the big luggage items that you will have to hand over at the airlines check in counter. Most of the airlines allow 2 big baggages as the check in luggage. Total linear dimensions (length+height+width) of each checked in baggage must not exceed 158 cm (62 inches), and weight of each bag must not exceed 32-35 kgs (70-77 pounds).
** 1 check in bag of total linear dimensions (45 inches) and weight 14 to 20kgs (30-40 pounds) is allowed for children not entitled for a separate seat. Plus you can carry a pram (stroller) or carrying basket.
** This is only generalized information, it may differ from airline to airline, confirm it beforehand. Due to rough handling some luggage may be damaged. If your luggage is not very strong tie it properly with a rope.
What should be carried in the hand baggage?

You should keep all your important documents, medicines and two pairs of clothes. If your destination is a cold place, then include sufficient woollens, that is, sweater, jacket, gloves, socks, cap etc.

While you are at the departure Airport

You have to go through few formalities before boarding the plane.

Step 1:	You need to scan your luggage in the X-ray machine close to your airlines check in counter. Here the person in charge will put a safety-checked sticker on the luggage. (No need to X-ray the hand luggage here.)
Step 2:	Keep your passport, ticket and a pen handy.
Step 3:	At the check in counter, hand over your luggage for check in. Take the boarding pass, ask for your seat preference, ask for transit details (if you have any flight change in between), and take a receipt of your checked-in luggage. (**Make sure that destination stamped on it is correct, otherwise you will lose it). You will get a Embarkation form here, fill it carefully in all capital letters clearly. If you have any confusion, ask the airline staff. Now, you may proceed to the immigration counter.
Step 4:	Immigration check. Here the immigration officer will ask for your passport, ticket, boarding pass and the Embarkation form. He might ask few questions about your journey, visa, purpose of travel etc. Answer clearly. He will take the Embarkation form, and will return every thing else after stamping your passport. Now proceed to the custom counter.
Step 5:	If you have lots of jewellery or any other expensive items with you, you can declare it at the customs counter, and get it endorsed on your passport. So when you come back, you will not have to face customs hassles. Here the custom officer will stamp your boarding pass. Now proceed to the security check.
Step 6:	Here you have to X-ray your cabin luggage, purse, or anything that you are carrying in your hand. Then you have to pass through a metal detector, where a personal security check will be done. The officer in charge will put a "security checked" stamp on your boarding pass. Collect back all your stuff. Now you are all set to board the plane.
Step 7:	Check for the departure gate number written on your boarding pass, and go to that gate. Now wait till the boarding is announced.
Step 8:	Once you are in the flight, look for the seat number mentioned on your boarding pass. If there's any problem, contact the cabin crew. They will also help you place the baggage in the overhead bins. Read the safety instruction booklet. In the plane you will be served food, snacks, drinks etc., from time to time. You will be given a blanket and a pillow. ** Important: In case of any problem, or query during your flight, don't hesitate to ask the staff.

At the Intermediate/Transit Airport

If you have to change the flight at the intermediate airport then:

Step 1:	As soon as you reach the intermediate/transit airport, first thing you must do is to look for the Terminal and Gate number of your next flight.
Step 2:	All airports normally have a very good map and direction instructions. But in case of any problems, ask the airport staff.
Step 3:	Once you find the gate, then depending on the time you have, you can relax or shop at the airport. But, be at your gate 40 minutes prior to the flight time, as they require some time to check your tickets etc.
Step 4:	You won't have to do any other formalities here, apart from passing through the metal detector, and X-ray of your hand baggage.

** In case you have to change the terminal, then first find out information about the connecting airport shuttle to the respective terminal. It is always advisable to find out such information beforehand, as in some countries, you may need a Transit Visa to leave one airport, to go to the other one.

Before you reach destination:

In Flight

Few hours before arrival, the flight attendants will give you
give you two forms to fill. One will be the US custom form, and the other will be the immigration ( I-94 ) form. Fill them very carefully.
Sample : this is how I-94 Form and USA Custom Form look like.

If you have questions, dont hesitate to ask any co-passenger and aks for the help to fill the forms correctly.

When you reach your Destination Airport

Step 1:	Immigration counter. Here, the inspector will check your passport and the immigration form. He might ask a few questions about your visa status, purpose of visit, address of stay, duration of stay etc. Answer them very carefully, and politely. The officer will attach a part of I-94 form you filled, to your passport. You will also be aksed for digital fingerprint and a photograph. Now on your way, you will find a custom officer. ** Remember: The counter slip of I-94 is very important. Check for visa status, and expiry date, written by the officer on it.
Step 2:	Collect a baggage trolley and go to the baggage collection counter, find your baggage with your flight number displayed on the tag. Collect your baggage. Note: At some airports, there are charges for taking trolley/cart viz. 1or 2 Dollar or so. Hence keep some change handy.
Step 3:	The custom officer will ask for the custom form. Now proceed towards the "Exit" gate.
Step 4:	If you are expecting somebody to receive you, you might find them here in this lobby. If not, you may go to the information counter desk, and enquire about the transport information.

** Remember: If you are questioned by the airport officers, answer them properly without any fear. But be careful, there should not be any discrepancy in the information stated in your documents and what you answer. It has happened in few cases, that due to the unsatisfactory answers about the stay, status, etc. people have been deported immediately. For instance, don't ever say, you will work here, if you hold H4, L2, B1 or visitor visa.
US Custom related questions:
Checkout the frequently aksed question and answers about US custom.

How to make a Call to other coutires From the Airport?

Option1: You can make a call anywhere in the world from most of the airport public booths using visa/master cards. You will find dial-in instructions be on the phone.
Option2: Buy calling cards from the shops inside the terminal. It's always better to carry some $5 or $10 bills. Dial-in instructions will be on the card.
Option3: Those who can avail AT&T calling Card, can carry AT&T calling card that can be used internationally. Usually along with the card you get the dial-in instruction of various countries.

Useful Tips:
Here is some useful english differences / terminology you may find very useful during your flight or at the airport. Specilly if your destination is USA and travelling by a USA airlines.

Indian English	American English
Luggage	Baggage
Air Hostess	Flight Attendant
Soft drink / Cold drink	Soda / Drink
Film	Movie
Dollar Note	Dollar Bill
Bathroom	Restroom
Tea	Hot Tea
Milk for Tea or Coffee	Creamer
Plain water	Water with no Ice

You can find more : More commonly used english words and differences.

Frequently Asked Questions

What if at the last moment, they ask you to give your cabin bag as checkin luggage?

Sometimes, it happens that at the last minute you may be asked to checkin your cabin bag. You may have some important documents and jewelry in it. So don't panic, in such case insist that you want to keep them with you. Remember you are doing a favor to them by traveling by their airlines and not vice versa, so politely try to talk them about your problem.

What if you lose your luggage?

Normally, this doesn't happen. In case you do not find your checkin luggage, inform the airlines authorities. If it is misplaced during transit or in the airlines, then it will be delivered to your address in a few days. If it is delayed for more then 2 days or so, You may ask for the compensation to buy daily necessary stuff, till you get your luggage back.

If it is missing for ever, they will compensate according to their nominal rules.
What if your flight is delayed or canceled?

In case your flight is delayed because of bad weather, or any other reason, airlines might offer you food, and make arrangements for your stay.

What if you miss your flight?

Talk to the airlines staff or authorities at the airport, they should be able to send you on the next available flight, or make some other other alternative arrangements.

What if nobody comes to receive you at the airport?<

Find out information from the Information Counter, about the taxi stand or the airport shuttle schedules. It's always better to have a complete address of your stay. Try to get driving directions from the web sites like yahoo etc. These directions can be useful for the driver to take you to the right place.

Bon Voyage!

IIS 6.0 Resource Kit Tools

2010-03-24T21:26:00.002+05:30

http://support.microsoft.com/kb/840671

Performance Tuning in IIS 6.0

2010-03-24T21:21:00.001+05:30

http://www.iisfaq.com/Default.aspx?tabid=2508

Web server administrators often monitor their Web servers to create a performance baseline. A performance baseline is a collection of data that indicates how the servers are performing when everything is running smoothly. Before making changes to their servers in a production environment, administrators tune their servers in a test environment to achieve the established performance baseline. By tuning their servers, Web server administrators maximize the Web server's ability to handle HTTP requests and minimize Web application response times, which create a better experience for clients accessing their Web servers.

In This Section

This section includes the following information:

Using HTTP Compression: Describes how to improve performance between client computers and servers by reducing file sizes before the files are sent to the client computer. Reducing the file size as described here is referred to as compression.
Enabling HTTP Keep-Alives: Describes how to use HTTP Keep-Alive requests to maintain an open connection.
Limiting Connections: Describes how to set limits on the number of connections to a Web server.
Setting Connection Timeouts: Describes how to set connection time-out values on a Web server.
Throttling Bandwidth: Describes how to change the bandwidth used by a Web server and individual Web sites.
Setting the IIS Object Cache Time Period: Describes how to set the IIS object cache time period.
Maximizing Data Throughput for Network Applications: Describes how to maximizing data throughput for network applications.
Setting the SSL Cache Time-out Interval: Describes how to set the SSL cache time-out interval.
Measuring Load Time for a Web Page: Describes how to measure load time for a Web page.
Enabling CPU Monitoring in IIS 6.0: Describes how to monitor and stop problematic applications.
Configuring Application Pool Queue-Length Limits: Describes how to limit the number of requests IIS stores in any application pool queue so the requests do not grow to such a large size as to exhaust server resources.
Scalability: Provides information and links to detailed resources about scalability.
Configuring Last-Modified Caching: Describes how to configure last-modified caching.
Configuring ASP Change-Notification Caching: Describes how to configure ASP change-notification caching.

Related Sections

For more information about each of the performance features described in this section and for a more detailed introduction into what it means to monitor and tune an IIS Web server, see Optimizing IIS 6.0 Performance.
For more information about performance tuning, how to work with counters, how to create and configure counters, trace logs, or alerts, and a list of best practices; see "Monitoring Performance" in Help and Support Center for Windows Server 2003.
For information about monitoring the performance of your ASP.NET applications, see Overview of ASP.NET Performance Monitoring.
For more information about the Web Capacity Analysis Tool for performance testing and monitoring, download the IIS 6.0 Resource Kit Tools and their accompanying documentation.

How to use ADPlus to troubleshoot "hangs" and "crashes" ?

2010-03-24T21:18:00.000+05:30

Suimmary :

ADPlus is a tool from Microsoft Product Support Services (PSS) that can troubleshoot any process or application that stops responding (hangs) or fails (crashes). Frequently, you can use ADPlus (ADPlus.vbs) as a replacement tool for the Microsoft Internet Information Server (IIS) Exception Monitor (6.1/7.1) and User Mode Process Dump. These are two separate tools that PSS frequently uses to isolate what causes a process to stop responding (hang) or quit unexpectedly (crash) in a Microsoft Windows DNA environment.

When should you use ADPlus?

ADPlus is intended to provide Microsoft PSS support professionals with debugging information that they must have to isolate the cause of problems that occur in complex environments.

Use ADPlus to capture debugging information if you are experiencing the following problems:

Processes that stop responding.

Processes that consume 100 percent CPU on a single processor computer, 50 percent CPU on a dual processor computer, 25 percent CPU on a quad processor computer, and so on.

Processes that crash or shut down unexpectedly.

Where do you obtain ADPlus?

ADPlus is included with the latest Microsoft Debugging Tools for Windows. To obtain the latest Microsoft Debugging Tools for Windows, visit the following Microsoft Web site:

http://www.microsoft.com/whdc/devtools/debugging/default.mspx

What needs to be backed up in IIS 6.0 ?

2010-03-24T21:14:00.001+05:30

refer : http://blogs.iis.net/chrisad/archive/2006/08/21/1376661.aspx

Diaster recovery - http://technet.microsoft.com/hi-in/magazine/2006.08.saveyourweb(en-us).aspx

Last year, I did a presentation in the IIS Webcast Series called “Disaster Recovery and IIS 6.0: Metabase backups in a Nutshell.” The main reason I put that webcast together is to ensure that customers had prescriptive guidance on the “what” & “how” of doing backups of IIS servers.

The key understanding is that IIS is a part of the operating systems and has many, many dependencies on that platform. A person tasked with understanding a organizations backup strategy cannot overlook this simple fact. This webcast spent some time discussing backups but did so by looking at three major pieces:

IIS Web Content (i.e. inetpub\wwwroot)
IIS Configuration (i.e. metabase.xml)
Operating System Components (i.e. Certificates, COM+, etc.)

During this presentation, I talked about and delivered a sample script that customers can use to back up these pieces of information. I also explained the how & why of each part. I felt that I could summarize here -

IIS Web Content

This is the single most important asset a company has. The intellectual property of the site is completely built around the content that host the companies website. The content, though, goes beyond just web pages, but images, documents, privacy information, etc. In the world of Web Farms, it is important to ensure that everything is in sync. To facilitate a backup strategy, a step that could be taken would to centralized content on a UNC Share. This feature was enhanced significantly in IIS 6.0. This certainly makes backups easy, but there are architectural understandings that need to be known before jumping into UNC scenarios.

Thus, UNC is good for backups in web farm scenarios. However, hosting content locally does not make it impossible. There are several good utilities out there to copy data, but I stick with xcopy as it does a lot of the greatness I was looking for.

IIS Configuration

You cannot over-emphasize how important backing up the metabase is. In my early days in PSS (circa 2000), I was stunned at the amount of IIS 5.0 customers that did not have a backup of the metabase. The task was fairly simple as it was a single file, metabase.bin, but was hidden in the IIS Manager (UI). To do it (same for IIS 6.0 except choose Web Sites node, not server), right-click on the server, choose All Tasks, and select Backup\Restore option. This will create a backup in the %systemroot%\system32\inetsrv\metaback directory.

In IIS 6.0, we built a nice scriptable command-line utility called iisback.vbs. This can be called throughout any script, such as prior to modifying the configuration, and after if it succeeds. The biggest problem that plagues IT professionals today when backing up IIS is the lack of understanding of “SecureProperties.” There are certain pieces of data that is stored in the metabase that is considered protected, such as passwords, etc. We store the passwords for the anonymous user account (Metabase Property: AnonymousUserPass) and process identities (Metabase Property: WamUserPass). These are not the only properties, but possibly the most sensitive since you can obtain credentials for logging on the server. To protect against this, this data is protected via a hash using the Operating System’s cryptography. This security causes confusion. In short, each installation of Windows has a unique key that can be called for hashing and protection of data. This unique key is lost when machines are “rebuilt” or destroyed by a disaster. A complete, and this does mean complete, backup can be used to restore this functionality using NTBackup or say Veritas’s BackupExec. This is risky though. The overall suggestion for quick & dirty restores is to simply understand how to backup the system and remove this uniqueness. This feature is natively available in the IIS 6.0 user interface but also in iisback.vbs. In my sample script below, I use this feature of providing a password for the backup and remove any use of the system’s cryptography.

Operating System

Certificates

There is nothing worse than getting a call\email from a customer who did all of the above (backup content & config) and has one single problem. I am back up and running but none of my Secure Socket Layer (SSL) sites are working. The answer is not a pretty one but one that happens way too often — they failed to remember this in their disaster planning. It is important that certificates are backed up very regularly as they can become corrupt, etc. with very little notice.

Using the Certificates Snap-in (http://support.microsoft.com/kb/q232136/), you can back up the certificates one by one. However, we shipped a cool tool as part of the IIS 6.0 Resource Kit Tools called IIsCertDeploy.vbs. This is a very useful and powerful tool that allows you manage, backup, and restore your certificates. In my script below, I use this tool to export the certificate to a .pfx file that can later be restored in case of failure.

COM objects

With the evolution of the old-time WinDNA architecture, a key aspect of web development came from the creation of a set of components that housed the business logic. The content covered in part I of this piece would only reference these objects that are essentially a component dll that implements logic and communication to the backend databases. There is no less of a sinking feeling of getting everything restored and firing through your application and getting the horrific error:

ERROR_OBJECT_NOT_FOUND

This means nothing more than you are missing the component. In this case, you have to rebuild the component services application to ensure the settings are the same, etc. Do you have this documented? If not, there is a means of creating a COM+ MSI that you can later use to restore these components — very cool!

REM******************************************
REM
REM My IIS Backup File
REM
REM******************************************
REM
REM Get SSL Certificates
REM ------------------------------------------------------
iiscertdeploy.vbs -e d:\webbackups\certs\site1.pfx -i w3svc/1 -p site1pwd -q On
iiscertdeploy.vbs -e d:\webbackups\certs\Site2.pfx -i w3svc/1856130344 -p site1856130344pwd -q On
REM
REM Backup IIS Metadata
REM -------------------------------------------------------
iisback /backup /b MyMetaBackup /e BackupPass /overwrite
xcopy %windir%\system32\inetsrv\metaback\MyMeta*.* d:\webbackups\metadata /Y
REM
REM Copy COM MSI File(s)
REM
xcopy d:\foo.msi d:\webbackups\COM+
REM
REM Copy all Content, Certs, Metadata, and Content to UNC Share
REM --------------------------------------------------------
net use o: \\server\mybackups xcopy /o /x /e /h /y /c d:\WEBBACKUPS\metadata\*.* o:\Metadata\
xcopy /o /x /e /h /y /c d:\inetpub\wwwroot\*.* o:\content\
xcopy /o /x /e /h /y /c d:\WEBBACKUPS\COM+\*.* o:\COM+\
xcopy /o /x /e /h /y /c d:\WEBBACKUPS\certs\*.* o:\certs\
net use o: /delete /Y

Summary

Recently, I wrote up a quick article that was published in Technet Magazine called Plan Ahead to save your Web. It is similar in nature but in the end game simply says - be prepared, be very prepared. Happy Backups...

How to backup and restore IIS 6.0 Metabase ?

2010-03-24T20:57:00.001+05:30

1) Open IIS Manager
2) Right Click on Local Computer -> All Tasks -> Backup/Restore Configuration

3) Under Configuration backup name type a name for your backup
4) Select Encrypt backup using password and type your password twice

5) Start -> Run -> %systemroot%\system32\inetsrv\MetaBack
6) Copy to the new server the two ackup files created under the name you give with extensions .SC0 and MD0
7) Copy all your web folders to the new server

Restoring IIS 6.0 Metabase on new server please use following steps

1) Restore all your web folders back to the new server
2) Open IIS Manager
3) Second Mouse Click on Local Computer -> All Tasks -> Backup/Restore Configuration

4) Select the file you want to restore and enter the password when prompt

After restoration is complete be sure that you have installed latest Framework 3.5 SP1 and in case you have the sites connected to an external sql database you double check your configuration changes.

update me if you required further assistance on this.

Status Error Codes and Reasons

2010-03-22T20:21:00.001+05:30

Status-Code = Reasons

"100" ; Section 10.1.1: Continue

"101" ; Section 10.1.2: Switching Protocols

"200" ; Section 10.2.1: OK

"201" ; Section 10.2.2: Created

"202" ; Section 10.2.3: Accepted

"203" ; Section 10.2.4: Non-Authoritative Information

"204" ; Section 10.2.5: No Content

"205" ; Section 10.2.6: Reset Content

"206" ; Section 10.2.7: Partial Content

"300" ; Section 10.3.1: Multiple Choices

"301" ; Section 10.3.2: Moved Permanently

"302" ; Section 10.3.3: Found

"303" ; Section 10.3.4: See Other

"304" ; Section 10.3.5: Not Modified

"305" ; Section 10.3.6: Use Proxy

"307" ; Section 10.3.8: Temporary Redirect

"400" ; Section 10.4.1: Bad Request

"401" ; Section 10.4.2: Unauthorized

"402" ; Section 10.4.3: Payment Required

"403" ; Section 10.4.4: Forbidden

"404" ; Section 10.4.5: Not Found

"405" ; Section 10.4.6: Method Not Allowed

"406" ; Section 10.4.7: Not Acceptable

"407" ; Section 10.4.8: Proxy Authentication Required

"408" ; Section 10.4.9: Request Time-out

"409" ; Section 10.4.10: Conflict

"410" ; Section 10.4.11: Gone

"411" ; Section 10.4.12: Length Required

"412" ; Section 10.4.13: Precondition Failed

"413" ; Section 10.4.14: Request Entity Too Large

"414" ; Section 10.4.15: Request-URI Too Large

"415" ; Section 10.4.16: Unsupported Media Type

"416" ; Section 10.4.17: Requested range not satisfiable

"417" ; Section 10.4.18: Expectation Failed

"500" ; Section 10.5.1: Internal Server Error

"501" ; Section 10.5.2: Not Implemented

"502" ; Section 10.5.3: Bad Gateway

"503" ; Section 10.5.4: Service Unavailable

"504" ; Section 10.5.5: Gateway Time-out

"505" ; Section 10.5.6: HTTP Version not supported

Interview with HP Mphasis for IIS Admin Position

2010-03-22T20:11:00.005+05:30

Questions Asked for IIS Admin Position for HP Mphasis :

1) Tell About Yourself and Career

2) What versions of IIS have you worked on ?

3) What is the difference between IIS 5.0 and IIS 6.0 ?

4) How will you check the memory usage of 200 servers ?

5) How will you tune IIS to improve performance ?

6) What is the difference between .ASP & .ASPX file Extension ?

7) How will you setup SSL ? The whole process of getting a https website .

8) What is host header ?

9) Can multiple websites be hosted on a single IP ?

10) How will you assign SSL for 10 websites hosted in a single IP ?

Ans

11) What will you do if you see "Page cannot be displayed" ? How will you trouble shoot ?

Ans Ans2
12 )What is webgarden ?

13 ) What is the difference between Application Pool and Application Domain ?

14) What is "302" Error page ?

Ans : Moved temporily
15) What is incident management and change management ? (ITIL Process )

16) How will you move site from one server to another server ?

17) For Eg., You have 'test','prod' and 'dev' servers, how will you move the contents from 'test' to 'prod ' server ? (using FTP ?)

18) Maximum of how much RAM can be assigned to IIS ? (If a server has 3 GB RAM)

What is the difference between Application vs. AppDomain ?

2010-03-22T19:51:00.003+05:30

Application vs. AppDomain
=======================

A question was asked on a forum that I frequent which I thought was worth writting a blog about.

Q: What is the difference between an application and an Appdomain? I understand from my research so far that an Appdomain is a container within which ASPX runs and that Apppool is a process that starts the w3wp.exe worker process within which ASP applications run.

A: That's a good question. Here are some key differences:

· An application is an IIS term, but it's one that ASP.NET utilizes. Essentially it creates a sandbox, or a set of boundaries to separate different sites, or parts of sites, from the others.

· An AppDomain is a .NET term. (In IIS7, AppDomains play a larger role within IIS, but for the most part it's an ASP.NET term)

· An AppDomain contains InProc session state (the default session state mode). So if an AppDomain is killed/recycled, all of your session state information will be lost. (if you are using the default InProc session state)

· Applications can have multiple AppDomains in them although often times there is a one-to-one relationship between them.

· In IIS6 and greater, there is the option of creating groups, or "pools" of applications that can be bundled together or separated; however the server administer decides. These are called Application Pools. Each app pool runs under its own w3wp.exe worker process.

· In IIS, it's easy to see an application. A new website is a separate application and any subfolder can be marked as an application. When they are, the icon beside the folder turnes into a picture of some gears. By right-clicking on the folder, you have the option of marking a folder as an application or removing it as an application, if it already is one. Also, in IIS6, in the Application Pools section, you can see all of the applications and which app pool they live under.

· ASP.NET, on the other hand, doesn't give much visibility into AppDomains, at least not from any visual tools. This is done behind the scenes. Programmatically you can create them, tear them down or see a list of all running AppDomains.

· You can recycle an application from IIS. In IIS5, you can't do it directly unless you recycle the entire web server, but in IIS6 and greater, you can recycle the application pool that the application lives under. It will gracefully die off and a new application will start up to replace it. Or, to word it another way, another w3wp.exe worker process will be started and then the old one will die off after it completes any currently running page requests.

· You can recycle an AppDomain in ASP.NET through the 'touch trick'. There are a few ways to do it, but the most straight forward is to edit your web.config file in notepad and add a space to an insignificant place. Then save the file. This will cause the AppDomain to recycle. This *does not* touch the IIS application though.

· Recycling an AppDomain will come pretty close to starting ASP.NET fresh again for that particular ASP.NET application, so although it doesn't recycle the apppool, it can give ASP.NET a fresh start in many situations.

What ASP.NET Programmers Should Know About Application Domains In this article, we will discuss application domains in .NET, and how they impact your ASP.NET execution and deployments.

When we launch the Notepad program in Windows, the program executes inside of a container known as a process. We can launch multiple instances of Notepad, and each instance will run in a dedicated process. Using the Task Manager application, we can see a list of all processes currently executing in the system.

A process contains the executable code and data of a program inside memory it has reserved from the operating system. There will be at least one thread executing instructions inside of the process, and in most cases there are multiple threads. If the program opens any files or other resources, those resources will belong to the process.

A process is also boundary. Erroneous code inside of a process cannot corrupt areas outside of the current process. It is easy to communicate inside of a process, but special techniques are required to communicate from one process to another. Each process also runs under a specific security context which can dictate what the process can do on the machine and network.

A process is the smallest unit of isolation available on the Windows operating system. This could pose a problem for an ISP who wants to host hundreds of ASP.NET applications on a single server. The ISP will want to isolate each ASP.NET application to prevent one application from interfering with another company’s application on the same server, but the relative cost of launching and executing a process for hundreds of applications may be prohibitive.

Introducing the Application Domain

.NET introduces the concept of an application domain, or AppDomain. Like a process, the AppDomain is both a container and a boundary. The .NET runtime uses an AppDomain as a container for code and data, just like the operating system uses a process as a container for code and data. As the operating system uses a process to isolate misbehaving code, the .NET runtime uses an AppDomain to isolate code inside of a secure boundary.

Note, however, that the application domain is not a secure boundary when the application runs with full trust. Applications running with full trust can execute native code and circumvent all security checks by the .NET runtime. ASP.NET applications run with full trust by default.

An AppDomain belongs to only a single process, but single process can hold multiple AppDomains. An AppDomain is relatively cheap to create (compared to a process), and has relatively less overhead to maintain than a process. For these reasons, an AppDomain is a great solution for the ISP who is hosting hundreds of applications. Each application can exist inside an isolated AppDomain, and many of these AppDomains can exist inside of a single process – a cost savings.

AppDomains And You

You’ve created two ASP.NET applications on the same server, and have not done any special configuration. What is happening?

A single ASP.NET worker process will host both of the ASP.NET applications. On Windows XP and Windows 2000 this process is named aspnet_wp.exe, and the process runs under the security context of the local ASPNET account. On Windows 2003 the worker process has the name w3wp.exe and runs under the

NETWORK SERVICE account by default.

An object lives in one AppDomain. Each ASP.NET application will have it’s own set of global variables: Cache, Application, and Session objects are not shared. Even though the code for both of the applications resides inside the same process, the unit of isolation is the .NET AppDomain. If there are classes with shared or static members, and those classes exist in both applications, each AppDomain will have it’s own copy of the static fields – the data is not shared. The code and data for each application is safely isolated and inside of a boundary provided by the AppDomain

In order to communicate or pass objects between AppDomains, you’ll need to look at techniques in .NET for communication across boundaries, such as .NET remoting or web services.

Note again: the one caveat to the idea of an AppDomain as a boundary is that ASP.NET applications will run with full trust by default. Fully trusted code can execute native code, and native code can essentially have access to anything inside the process. You’ll need to run applications with partial trust to restrict access to unmanged code and verify all managed code to secure AppDomains.

Shadow Copies and Restarts

Once an assembly is loaded into an AppDomain, there is no way to remove the assembly from the AppDomain. It is possible, however, to remove an AppDomain from a process.

If you copy an updated dll into an application’s bin subdirectory, the ASP.NET runtime recognizes there is new code to execute. Since ASP.NET cannot swap the dll into the existing AppDomain , it starts a new AppDomain. The old application domain is “drain stopped”, that is, existing requests are allowed to finish executing, and once they are all finished the AppDomain can unload. The new AppDomain starts with the new code and begins taking all new requests.

Typically, when a dll loads into a process, the process locks the dll and you cannot overwrite the file on disk. However, AppDomains have a feature known as Shadow Copy that allows assemblies to remain unlocked and replaceable on disk.

The runtime initializes ASP.NET with Shadow Copy enabled for the bin directory. The AppDomain will copy any dll it needs from the bin directory to a temporary location before locking and loading the dll into memory. Shadow Copy allows us to overwrite any dll in the bin directory during an update without taking the web application offline.

Master Of Your Domain

Application domains replace the OS process as the unit of isolation for .NET code. An understanding of application domains will give you an idea of the work taking place behind the scenes of an ASP.NET application. Using the CurrentDomain property of the AppDomain class you can inspect properties about the AppDomain your code is executing in, including the Shadow Copy settings we discussed in this article.

What is ISAPI Filter ?

2010-03-19T00:50:00.001+05:30

ISAPI Filter Overview

ISAPI filters are DLL files that can be used to modify and enhance the functionality provided by IIS. ISAPI filters always run on an IIS server, filtering every request until they find one they need to process. The ability to examine and modify both incoming and outgoing streams of data makes ISAPI filters powerful and flexible.

Filters are registered at either the site level or the global level (that is, global filters apply to all sites on the IIS server), and are initialized when the worker process is started. A filter listens to all requests to the site on which it is installed.

Both ISAPI filters and ISAPI extensions can only be developed using C/C++. Visual Studio comes with wizards that make ISAPI development fast and easy.

Possible Uses for ISAPI Filters..

ISAPI filters can be registered with IIS to modify the behavior of a server. For example, filters can perform the following tasks:

Change request data (URLs or headers) sent by the client
Control which physical file gets mapped to the URL
Control the user name and password used with anonymous or basic authentication
Modify or analyze a request after authentication is complete
Modify a response going back to the client
Run custom processing on "access denied" responses
Run processing when a request is complete
Run processing when a connection with the client is closed
Perform special logging or traffic analysis.
Perform custom authentication.
Handle encryption and compression.

Note:
ISAPI filter DLLs cannot be requested explicitly, like ISAPI extensions can.

ISAPI Filter Processing Sequence

Every ISAPI filter is contained in a separate DLL that must export two entry-point functions, GetFilterVersionand HttpFilterProc, and optionally export the TerminateFilter function. The metabase property, FilterLoadOrder, contains a list of all filters that IIS loads when the Web service is started.

The following steps outline the interaction between ISAPI filters and IIS:

When IIS initially loads an ISAPI filter, it also creates and partially populates an HTTP_FILTER_VERSION structure. It then calls the filter's GetFilterVersion function, passing a pointer to the new structure as a parameter.
The ISAPI filter populates the HTTP_FILTER_VERSION structure with version information and descriptive information. More importantly, the filter also uses HTTP_FILTER_VERSION to specify which event notifications it should receive, and to declare the general priority level for the filter. In addition, the filter also indicates whether it is interested in events from secure ports only, unsecure ports only, or both.
Each HTTP transaction between IIS and a client browser triggers several distinct events. Every time an event occurs for which an ISAPI filter is registered, IIS calls the filter'sHttpFilterProc entry-point function.
If more than one ISAPI filter is registered for a given event, IIS notifies the filters that the event occurred. The filters, which are marked as high, medium, or low priority, are notified according to priority in descending order. If more than one ISAPI filter is declared the same general priority level, IIS uses the order in which the filters appear in the FilterLoadOrderproperty to resolve the tie.
The ISAPI filter uses the notification type information, passed by IIS as a parameter to HttpFilterProc, to determine which particular data structure is pointed to by the otherHttpFilterProc parameter, pvNotification. The ISAPI filter then uses the data contained in that data structure, as well as in the context structure HTTP_FILTER_CONTEXT, to perform any custom processing.
Once processing is complete, the filter returns one of the SF_STATUS status codes to IIS, and IIS continues processing the HTTP request or response until another event occurs for which ISAPI filters are registered.
When the Web service is stopped or unloaded, IIS calls TerminateFilter in all ISAPI filters as part of its shutdown sequence, for any filters that implemented and exported the function.TerminateFilter is typically used to perform cleanup and de-allocation of allocated resources.

GetFilterVersion is called exactly once, when the ISAPI filter is initially loaded. Any per-connection initializations the developer wants to perform must be managed internally within the context of the HttpFilterProc function call.

Note:
The priority setting for ISAPI filters is per filter, not per notification. For example, a low priority rating cannot be assigned for one type of notification and a high priority rating for another type.

Installing a SSL certificate in a Dedicated IP

2010-03-17T21:03:00.003+05:30

1) Get A Dedicated IP
2) Purchasing an SSL certificate

Some hosting company can not provide you with a signed SSL certificate. You will need to obtain one from a valid SSL certificate authority. There are a number of certificate authorities to choose from.

Here are some other well known certificate authorities.

CSA - Certificate providing authority

Microsoft IIS 5 and 6 - Internet Information Services 5 and 6

Follow these instructions to generate a CSR for your Web site. When you have completed this process, you will have a CSR ready to submit to CPA in order to be generated into a SSL Security Certificate.

Note: If you are renewing your certificate or your site is currently running a web server certificate please refer to renewal section at the bottom of this document.

You must have at least Service Pack 1 installed

Select the Internet Information Services console within the Administrative Tools menu.
Select the computer and web site (host) that you wish to secure.
Right mouse-click to select Properties.
Select the Directory Security tab.
Select Server Certificate under Secure Communications
Click Next in the Welcome to the Web Server Certificate Wizard window.
Select Create a new certificate, Click Next.
Select Prepare the request now, but send it later.
At the Name and Security Settings screen, give your new certificate a name - this will help you identify this request if you work with multiple domain names on the same webserver. Select bit length. We recommend using 1024-bit length (note: To generate 128 bit encryption you will need to select a 1024 bit length). Click Next.
You will now be asked for details about your company and your website. When creating a CSR you must follow these conventions.
The following characters can not be accepted: < > ~ ! @ # $ % ^ * / \ ( ) ?&.
This includes commas.
At the Organization Information, state your Company Name and Department.

At the Your Site's Common Name screen, enter the domain name (e.g. yourdomain.com) or fully qualified domain name (e.g. www.yourdomain.com). Whatever you enter here will be exactly what the certificate will be able to be used on.
At the Geographical Information screen, enter your country, state and city.
You have now finished entering information. Your CSR will now be saved to a text file. Give your CSR a filename and select a location where you can easily find your CSR.
Important: Now review what you have entered. If you notice a mistake, use the Back button to return to the relevant screen to make changes. Pay particular attention to the Issued To field.
You have now generated your CSR! Click Finish to close the wizard.

IMPORTANT DO NOT REMOVE the pending request from your IIS or your issued certificate will not install. Attempting to create another CSR will automatically remove the pending request and this should be attempted until you have installed your issued certificate.

Install the certificate :

Select Administrative Tools
Start Internet Services Manager
Open the properties window for the website. You can do this by right clicking on the Default Website and selecting Properties from the menu.
Open Directory Security by right clicking on the Directory Security tab
Click Server Certificate. The following Wizard will appear:
Choose to Process the Pending Request and Install the Certificate. Click Next.
Enter the location of your IIS SSL certificate (you may also browse to locate your IIS SSL certificate), and then click Next.
Read the summary screen to be sure that you are processing the correct certificate, and then click Next.
You will see a confirmation screen. When you have read this information, click Next.
You now have an IIS SSL server certificate installed.
Important: You must now restart the computer to complete the install

Use "Wfetch" to Troubleshoot IIS connections

2010-03-17T20:18:00.002+05:30

Scenario : If you're having problems getting a particular workstation to connect to your Web site, it might not be the workstation's fault. You can use Wfetch to see if there's a problem on your IIS server. lets see how Wfetch works.

As reliable as Web browsers and Web servers have become over the last few years, the reality is that there are times when a client’s connection to a Web server simply may not work correctly. If only one client is having a problem connecting to your Web site but other clients aren’t displaying similar problems, you may be inclined to dismiss the problem as being a client problem rather than a server problem.

What if that client can connect to other Web sites but not to yours? Such a situation points more toward a Web server problem than a client problem. So what do you do when you see contradictory symptoms and there are no clear answers? One possible way of solving the problem is to use the Wfetch utility to troubleshoot possible Web server connection problems.
What is the Wfetch utility?

Wfetch is a free utility provided by Microsoft to help you troubleshoot HTTP connection problems by allowing you to view data, such as the HTTP header, that isn’t usually displayed through a Web browser. You can download Wfetch from Microsoft’s Download Center.

Microsoft doesn’t officially support Wfetch. According to the Microsoft Web site, Wfetch is provided on an as-is basis and is completely unsupported. So don’t expect to get any help from Microsoft if you have problems with Wfetch.

Another thing that you need to know is that there are some serious security risks associated with using Wfetch. If you’re planning on using Wfetch to solve a problem, I recommend installing the Wfetch utility in a nonproduction environment initially. The Wfetch program isn't actually installed on a server; instead, it runs on a workstation. The problem is that Wfetch has a habit of installing things like passwords and certificates into the workstation’s registry. In some situations, Wfetch stores user passwords in clear text in the system’s registry.
Installing Wfetch
To install the Wfetch utility, double-click on the executable file that you downloaded. You'll then be asked which folder the installation program should extract the files into. Once the files have been extracted, three files will be placed into a folder called CodeSign in the location that you’ve specified. Open the CodeSign folder and run the Wfetch.exe file to run the Wfetch utility.

After double-clicking on the Wfetch.exe icon, you’ll see the Wfetch user interface, shown in Figure A. Wfetch’s interface isn’t very user-friendly.

Figure A
The Wfetch user interface isn’t very intuitive.

Along the top row of the Wfetch user interface, you’ll see four buttons. The button on the far left is the New Document button. This is the button you’ll use to preserve the results of your last test. You’ll also use this button if you want to run a second test after your first one but want to have the results of the second test placed in a different log file.

The next button (with a big X on it) is used to abort the current test. The third button has the Refresh icon on it; it's used to rerun the last request. The last button is the Log Cleanup button. Clicking this button will clear the current log screen. Be careful about clicking this button accidentally, because the utility doesn’t ask you if you’re sure that you want to erase the log; it just does it.

The next major section of the Wfetch interface is the section in which you specify the Web site that you want to analyze. The Verb field refers to the HTTP verb that you want to test. HTTP verbs are commonly used to perform various actions within an HTTP request. For example, if you associate the HEAD verb with a resource, then HTTP will return only the header information. If you associate the GET verb with the same resource, then HTTP will return the header and usually a message body as well.

The Host field is where you specify the host that you’re connecting to. Usually, the host is specified in the form of either an IP address or a URL.

The Port field allows you to pass the HTTP request through a specific port. If you leave the value set to Default, the request will be passed through TCP port 80.

The Ver field refers to the HTTP version used by the Web server. Your choices are 1.0 and 1.1. If you aren’t sure what version of HTTP is being used, try using version 1.1.

Finally, the Path field refers to a specific resource on a Web server. For example, if you were trying to troubleshoot a specific Web page or Web resource, you might specify that page or resource from within the Path field. The path is especially useful if you’re addressing an internal Web server by IP address and that server hosts several Web sites.

You could specify the IP address in the Host field and the Web site name in the Path field. For example, let’s say you want to test SharePoint Portal Server. To access the SharePoint default dashboard through Internet Explorer from your workstation, you’d enter the server name followed by the dashboard’s site name (bart.test.com—test in my example). To run the Wfetch utility against the dashboard site, you’d typebart.test.com into the Host field and type /test into the Path field, as shown in Figure B.

Figure B
The Path field is used to specify a Web site on an IIS server or a specific Web page within a Web site.

The next part of the Wfetch user interface is the Authentication section. This section allows you to control how the credentials that the Wfetch utility will use to access the host in question. For example, you might have noticed in Figure B that the default choice is Anonymous. If your Web site has anonymous authentication, you’d just leave the default settings.

Other available authentication types include Basic, NTLM, Kerberos, Digest, and Negotiate. If you choose to use any access method other than Anonymous, you must fill in the domain name, username, and password in the space provided beneath the authentication type. If you look at Figure B, you’ll notice that there’s a Save check box directly across from the Password field. If you select the Save option, your password will be saved in the registry in clear text, regardless of what authentication type you’re using. So make sure you heed my advice and check the registry when uninstalling the Wfetch utility.

The next area of the user interface is the Connection section. The Connection area allows you to configure how the Wfetch utility should attach to the host that you specified. The default options allow Wfetch to make a straight HTTP connection to the host. However, there is an option to pass the connection through a proxy server. If a proxy server, such as Microsoft's Proxy Server 2.0 or ISA Server, controls your Internet connection, you must select the Proxy check box and enter the port number used by the proxy server. By default, Proxy Server 2.0 uses port 80 while ISA Server uses port 8080.

Beneath the Connect field, you’ll see the Cipher field and Client Cert field. These fields exist because the Wfetch utility has the option of connection to a Web server using HTTP, HTTPS, PCT 1.0, SSL 2.0, SSL 3.0, or TLS 3.1. If you choose to use one of the secure protocols, you’ll have to select an encryption type from the Cipher drop-down list. Your choices include RC4, RC2, DES, and Triple DES.

The Client Cert field can be used only in conjunction with PCT 1.0, SSL 3.0, and TTLS 3.1 security. If you choose to use a certificate, you have several different options. The None option avoids using a certificate for the connection. The Certificate From IE option allows you to select one of the certificates that Internet Explorer is already configured to use. Should you choose this option, a dialog box will appear asking you to select the certificate. Once you’ve made your selection, a wizard will explain what to do next.

The Wfetch utility also gives you the option of using a valid certificate, an expired certificate, or an unrecognized certificate. Remember that you're testing a connection to a malfunctioning Web server, so there may very well be times when it’s appropriate to test the connection by using an expired or unrecognized certificate. The option of using a valid certificate presents the Web server with a Class 1 certificate that’s been signed by VeriSign. Although this certificate is intended to be valid, it’s hard coded into the utility and will therefore eventually expire.

You can check to make sure that the certificate is still valid by clicking on the arrow icon next to the Client Cert field. As you can see in Figure C, for example, my particular copy of Wfetch contains a certificate that expired in May of 2001. If your valid certificate has expired, then I recommend using an Internet Explorer-based certificate that is still valid.

Figure C
It’s possible that the certificate may have expired.

The only configuration-based section that remains is the Advanced Request section. This section allows you to do things like add headers, body, headers and body, or raw requests to the basic request. You can enable an advanced option simply by selecting it from the list. After choosing to make an advanced request, Wfetch gives you the chance to either type in the request or to copy code from an existing file. The advanced requests are entered into the text box found directly below the Advanced Request section.
Running a test
Now let’s run through the process of running a test so that you can see what the output looks like. I will show you a couple of problems to watch out for.

In Figure D, I am trying to run a Head test on my SharePoint Portal Server. Notice in the Authentication section that I have Anonymous access. SharePoint requires basic or NTLM authentication. So when I click the Go button to run the report, the Log Output section displays an HTTP/1.1 401 Access Denied message at the top of the text segment shown in blue. If a connection is failing due to security problems, this is what it will usually look like.

Figure D
This is what a security-related failure looks like.

The next thing that I want to show you is why the Path field is important. In Figure C, I was accessing the Test Web site on a server named Bart in the test.com domain. Normally, when accessing this Web site, I would type bart.test.com/test into Internet Explorer. However, in this case, I typed bart.test.com/test into the Host field rather than placing the /test parameter into the Path field where it belongs. Notice that the log section tells me that there is no such host. Obviously, the server and the corresponding Web site exist (and they are functional), but Wfetch reports that the host is unknown, as shown in Figure E, simply because I used an invalid method of addressing it.

Figure E
You’ll receive a host unknown error if you address the host incorrectly.

Now let’s look at a couple of successful tests. In Figure F, I’m using the HEAD verb to test my Web site. Notice in the figure that I’m using the Proxy option because I’m attaching to an external Web site.

Figure F
This is what a successful HEAD test looks like.

In Figure G, I’m doing the same test using the GET verb. In Figure F, the Wfetch tool returned information such as the Web server version and the date that the site was last modified. In Figure G, you can see that the same header information is displayed, but the tool also displays the HTML code found on the default Web page.

Figure G
The GET verb displays the header information and the Web site’s HTML code.

One last interesting thing to look at is the same test performed by using the TRACE verb. As you can see in Figure H, the TRACE verb allows you to watch the test as it passes from the proxy server to the Web and back.

Figure H
The TRACE test displays the actual connection process.

Fetch, Spot! Fetch!
The Wfetch utility is a useful tool for troubleshooting HTTP connection problems. The error reports it produces can help you figure out what’s wrong with your server. If you have problems understanding a particular error, you can use Microsoft’s Knowledge Base or Google to help you track down the error by searching for the error.

After you’ve used Wfetch to troubleshoot a problem, uninstall the utility immediately to prevent any security problems. Even after uninstalling the Wfetch utility, there’s a possibility that the registry keys containing the passwords could still exist. I recommend using the Registry Editor to check for the existence of this part of the registry and getting rid of the risky registry keys manually if necessary. The Wfetch registry keys are stored in HKEY_CURRENT_USER\Software\Wfetch. Keep in mind that if you’ve used Wfetch while logged on as multiple users, then this registry key may exist for each user you’ve logged on as.

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