The Voice of BIET..

CORE PHP PROGRAMMING, 3RD EDITION

2011-03-21T18:21:00.002+05:30

Fully revised for PHP 5

* The authoritative guide to real-world development with the new PHP 5

* Brand-new coverage of PHP design patterns, object techniques, and XML

* Updated coverage of syntax, functions, algorithms, and PHP software engineering

* Includes 650+ downloadable code examples

* Co-authored by Zeev Suraski, PHP 5 contributor and Zend Engine 2 co-creator

Praise for the third edition:

“In the Third Edition of Core PHP Programming, Leon has invited my partner Zeev Suraski to cover the PHP 5 language changes. Leon’s experience in writing PHP books and Zeev’s superior knowledge of PHP 5 and its internals have led to a must-buy book for PHP developers. I hope you enjoy this book and that it accompanies you during the adoption phase of PHP 5.”

—Andi Gutmans, PHP 5 contributor and Zend Engine 2 co-creator

The authoritative guide to PHP 5!

Master PHP 5, the easy, high-performance solution for enterprise-class Web development!

Core PHP Programming, Third Edition is the authoritative guide to the brand-new PHP 5. Top PHP developer Leon Atkinson and PHP 5 contributor/Zend Engine 2 co-creator Zeev Suraski cover every facet of real-world PHP development, from basic syntax to state-of-the-art design patterns.

It’s all here: networking, data structures, regular expressions, math, configuration, graphics, MySQL/PostgreSQL support, XML, algorithms, debugging, and much more. Discover how to build enterprise-class applications that use PHP 5’s breakthrough object-oriented features…and leverage the extraordinary Zend Engine 2 performance improvements this book’s co-author helped to implement.

Every Core Series book:

* DEMONSTRATES how to write commercial-quality code

* FEATURES nontrivial programs and examples—no toy code!

* FOCUSES on the features and functions most important to real developers

* PROVIDES objective, unbiased coverage of cutting-edge technologies—no hype!

Core PHP Programming, Third Edition delivers:

* Accurate, thorough coverage of PHP 5 syntax, functions, and algorithms

* Step-by-step guidance for PHP 5 database integration and XML development

* Best practices for software design, debugging, and integration

Click Here to Download

255 OF BEST PHP SCRIPTS FOR WEB DESIGNERS

2011-03-21T18:20:00.000+05:30

"Submit-A-Link" Style Script linksubmit.zip

"Suggest My Site" Script suggest.zip

"Users Online" Script #1 usersonline.zip

"Users Online" Script #2 cjusersonline.zip

Advanced Guestbook Script guestbook.zip

Affiliate Banner Rotation Script adrotator.zip

Affiliate Linkmaster affiliatemask.zip

Affiliate Program (Advanced Version) postaffiliate.zip

Affiliate Program (Basic Version) phpaffiliate.zip

Another PHP Web FTP Program webftp.zip

Auction Website phpauction.zip

Auto Hits Script scau.zip

Automated Form Submission Prevention human.zip

Bookmarks/Favorites Script bookmarks.zip

Build a Webring webring.zip

ClickBank "Thank You" Page Protector Script cbscript.zip

Client Invoicing Script myinvoice.zip

Document Management System sdms.zip

Easy Administration Program easyadmin.zip

EasyStream easystream.zip

Electronic Reminder Script ereminder.zip

Expired Domain Finder wgs-expire.zip

FAQ Generator whatdafaq.zip

FAQ Manager faqmanager.zip

FFA Links Page Script ffalinks.zip

File Transfer Script net2ftp.zip

Hot Mailing List Script newsletter.zip

ICQ Pager Script pager.zip

Image to ASCII Generator img2ascii.zip

Image Watermarking Script watermark.zip

Instant Photo Gallery Script instantgallery.zip

Instant Site Maker instantsm.zip

Link Listing Script links.zip

Links Exchange Website conservatory.zip

Live Help Script livehelp.zip

MySQL Database Backup Perl Script backupscript.zip

News Publishing Script topstory.zip

Office Intranet Suite intranet.zip

Online Classifieds Script classifieds.zip

Online MultiPlayer Chess webchess.zip

osCommerce PHP Shopping Cart oscommerce.zip

PassGen passgen.zip

PaymentPal paymentpal.zip

Perpetual Traffic Generator trafficgenerator.zip

PHP & MySQL Content Management System contentm.zip

PHP Form To Email Script SECURE! emailer.zip

PHP Message Boards Script messageboard.zip

PHP-based eCard Script/Website gcards.zip

POP-UP Creator popup.zip

Powerful Portal with Content Management phpx.zip

Secure Authentication Script authentication.zip

Simple Yet Powerful Download Counter Script hitcounter.zip

Sophisticated PHP Ecommerce Site xtcommerce.zip

Sports League, Fixture and Prediction Management Script phpfootball.zip

Toplist Website Manager #1 toplist.zip

Toplist Website Manager #2 topsites.zip

USENET News Client newsgroup.zip

Visitor Logging Script tollbooth.zip

Web Event Calendar calendar.zip

Web Portal System geeklog.zip

Web-Based Address Book Script wa-boo.zip

Web-based Image Management System photoseek.zip

Web-based POP Email Client webmail.zip

Website Stats Business trafficgopher.zip

Whois Lookup whois.zip

Yahoo Style Link Directory/Search Engine sslinks.zip

Download: | RAR | 40 MB | RS & MU |

Click Here to Download

PHP/MYSQL PROGRAMMING FOR THE ABSOLUTE BEGINNER

2011-03-21T18:18:00.001+05:30

If you are new to programming with PHP and MySQL and are looking for a solid introduction, this is the book for you. Developed by computer science instructors, books in the for the absolute beginner series teach the principles of programming through simple game creation. You will acquire the skills that you need for more practical programming applications and will learn how these skills can be put to use in real world scenarios. Best of all, by the time you finish this book you will be able to apply the basic principles you’ve learned to the next programming language you tackle.

Click here to Download

LEARNVISUALSTUDIO ASP.NET WEB MATRIX

2011-03-19T09:26:00.002+05:30

The Web Matrix is a free ASP.NET development tool. This series walks you through some of the basics of working with Web Matrix.

The following videos are available for this series:

Introduction to ASP.NET Web Matrix

A walkthrough of the entire Web Matrix application

ASP.NET Web Matrix Data Page Template Walkthrough

Demonstrates the use of 3 of the templates for creating Data based web pages in Web Matrix

ASP.NET Web Matrix Data Page Template Walkthrough Part 2

Demonstrates the use of 4 of the 7 Data Page templates in Web Matrix.

Click here to Download

ASP.NET AJAX 101 FROM LEARNVISUALSTUDIO.NET

2011-03-19T09:23:00.002+05:30

This series focuses on the ASP.NET AJAX Framework ... the API formerly known as "Atlas" which is now part of ASP.NET in Visual Studio 2008 (and Visual Web Developer 2008 Express Edition). While most of the available video material on Microsoft's site focuses on the Ajax Control Toolkit, this series dives into the underpinnings of the Framework, the JavaScript language extensions and more.

ASP.NET AJAX 101 - Lesson 1 - Video 1 - An Introduction to AJAX

ASP.NET AJAX 101 - Lesson 1 - Video 2 - Installing and Using the Web Development Helper Utility

ASP.NET AJAX 101 - Lesson 1 - Video 3 - Understanding the AJAX Traffic Footprint

ASP.NET AJAX 101 - Lesson 1 - Video 4 - Understanding Asynchronous Ajax Calls

ASP.NET AJAX 101 - Lesson 2 - Video 1 - Creating and Consuming PageMethods

ASP.NET AJAX 101 - Lesson 2 - Video 2 - An Alternative Approach to Consuming PageMethods

ASP.NET AJAX 101 - Lesson 2 - Video 3 - Creating and Consuming AJAX Enabled WFC Web Services

ASP.NET AJAX 101 - Lesson 2 - Video 4 - Providing User Feedback

ASP.NET AJAX 101 - Lesson 2 - Video 5 - Error Handling Using the ASP.NET AJAX Framework

ASP.NET AJAX 101 - Lesson 2 - Video 6 - Handling Timeouts

ASP.NET AJAX 101 - Lesson 3 - Video 1 - Understanding the Script Manager & How To Add Script References

ASP.NET AJAX 101 - Lesson 3 - Video 2 - Understanding the ScriptManagerProxy Control

ASP.NET AJAX 101 - Lesson 3 - Video 3 - Enabling Script Localization

ASP.NET AJAX 101 - Lesson 3 - Video 4 - Enabling Script Globalization

ASP.NET AJAX 101 - Lesson 4 - Video 1 - Introducing the UpdatePanel Control

ASP.NET AJAX 101 - Lesson 4 - Video 2 - Using UpdatePanel Triggers

ASP.NET AJAX 101 - Lesson 4 - Video 3 - Programmatic Regions

ASP.NET AJAX 101 - Lesson 4 - Video 4 - Programmatic Updates

ASP.NET AJAX 101 - Lesson 4 - Video 5 - Aborting UpdatePanel Requests

ASP.NET AJAX 101 - Lesson 4 - Video 6 - Registering DataItems

ASP.NET AJAX 101 - Lesson 5 - Video 1 - Error Handling with the ScriptManager

ASP.NET AJAX 101 - Lesson 5 - Video 2 - Handling Errors with Client Script

ASP.NET AJAX 101 - Lesson 6 - Video 1 - Using the UpdateProgress Control

ASP.NET AJAX 101 - Lesson 6 - Video 2 - Using the Timer Control

ASP.NET AJAX 101 - Lesson 7 - Video 1 - Using the Authentication Service

ASP.NET AJAX 101 - Lesson 7 - Video 2 - Using the Profile Service

ASP.NET AJAX 101 - Lesson 7 - Video 3 - Using the Roles Service

ASP.NET AJAX 101 - Lesson 8 - Video 1 - Creating a Custom AJAX Extender - Part 1

ASP.NET AJAX 101 - Lesson 8 - Video 2 - Creating a Custom AJAX Extender - Part 2

ASP.NET AJAX 101 - Lesson 8 - Video 3 - Exploring the Use of Client Side Classes

ASP.NET AJAX 101 - Lesson 8 - Video 4 - Creating a Custom AJAX Control

ASP.NET AJAX 101 - Lesson 8 - Video 5 - Extending an AJAX Control

Click here to Download

COLLECTION OF IT EBOOKS (.NET, C#, C++, JAVA, PHP, CSS, WEB DESIGN, SECURITY,...)

2011-03-18T10:52:00.000+05:30

http://rapidshare.com/files/175286628/dot_NET-Collection.part1.rar
http://rapidshare.com/files/175293075/dot_NET-Collection.part2.rar
http://rapidshare.com/files/175299455/dot_NET-Collection.part3.rar
http://rapidshare.com/files/175300605/dot_NET-Collection.part4.rar

GOOGLE EARTH PICS OF JAPAN BEFORE AND AFTER THE TSUNAMI

2011-03-18T10:50:00.000+05:30

LEARNING AND PROGRAMMING C SHARP EBOOK COLLECTION

2011-03-16T14:37:00.000+05:30

Learning and Programming C Sharp Ebook Collection
English | PDF & CHM | 1.49 GB
All kinds of C Sharp books, for everybody who wants to program C Sharp. from "for dummies" to mastering bibles...

Booklist

(Ebook - Pdf) - 70-316 Mcsd Mcad - Correctexams - Developing Windows Applications With C Sharp (Ver 6.0).pdf

(Ebook - Pdf) Msdn Training - Introduction To C Sharp Programming For The Microsoft .Net Platform.pdf

(Ebook - Pdf) Programming C Sharp, 2nd Edition (O'reilly).pdf

(Ebook Pdf) Deitel - C Sharp How To Program (Redistilled In One Book).pdf

(Ebook Pdf) Ms Press Programming Windows With C Sharp By Ch Petzold.pdf

(Ebook Pdf) Visual Studio C Sharp Book.pdf

(Ebook) C Sharp - Introduction To Design Pattern In C Sharp Vol_2 - Ibm.pdf

(Ebook) Professional C Sharp - Graphics With Gdi.pdf

(Ebook).Thinking.In.C Sharp.(Revision.1).pdf

(Ebook-.Net-C Sharp) C Sharp Com+ Programming .pdf

070-315 - Web Apps With C Sharp.pdf

070-316 - Windows Apps With C Sharp.pdf

070-320 - Web Services With C Sharp.pdf

2000 - Apress - A Programmer's Introduction To C Sharp.pdf

2000 - Apress - A Programmer's Introduction To C Sharp.pdf

2000 - Ms - C Sharp Language Reference.pdf

2001 - Hm - C Sharp Com+ Programming.pdf

2001 - Msdn - C Sharp Essentials Of Object-Oriented Programming.pdf

2001 - O'Reilly - C Sharp Essentials 2nd Edition.chm

2001 - O'reilly - Programming C Sharp.pdf

2002 - Apress - .Net Security.chm

2002 - Apress - Advanced Net Remoting (C Sharp Edition).chm

2002 - AW - C Sharp Developer's Guide to ASP.NET, XML, and ADO.NET.chm

2002 - Aw - C Sharp Primer, A Practical Approach.pdf

2002 - Hm - C Sharp, Your Visual Blueprint For Building .Net Applications.pdf

2002 - Ibm - Introduction To Design Patterns In C Sharp.pdf

2002 - Mcgraw - Advanced C Sharp Programming.pdf

2002 - Mh - Advanced C Sharp Programming.pdf

2002 - Microsoft - Programming Microsoft Windows With C Sharp.pdf

2002 - MS - Developing Windows-Based Applications with MS Visual Basic .NET and MS Visual C Sharp .NET.chm

2002 - Ms - Ms Visual C Sharp Net.chm

2002 - Msdn - Programming With C Sharp.pdf

2002 - O'reilly - C Sharp In A Nutshell.chm

2002 - O'Reilly - C Sharp Language Pocket Reference.chm

2002 - O'Reilly - Learning C Sharp1.chm

2002 - Premier - Microsoft C Sharp Programming For The Absolute Beginner.pdf

2002 - Premier - MS C Sharp Programming for the Absolute Beginner.chm

2002 - Sams - Teach Yourself C Sharp In 24 Hours.chm

2002 - Syngress - C Sharp.Net Web Developers Guide.pdf

2002 - Wiley - C Sharp Bible.pdf

2002 - Wiley - Professional C Sharp, 2nd Edition.chm

2002 - Wrox - C Sharp Today.chm

2003 - AW - .NET - A Complete Development Cycle .chm

2003 - AW - .NET for Java Developers - Migrating to C Sharp.chm

2003 - Aw - Essential Asp Net With Examples In C Sharp.chm

2003 - Aw - From Java To C Sharp - A Developer's Guide .chm

2003 - Aw - The C Sharp Programming Language.chm

2003 - Aw - Windows Forms Programming In C Sharp.chm

2003 - Ms - Asp Net Programming With Visual C Sharp Net 2003 Step By Step.chm

2003 - Ms - Ms Visual C Sharp Net Step By Step - Version 2003.chm

2003 - O'Reilly - C Sharp in a Nutshell, 2nd Edition.chm

2003 - O'reilly - Programming C Sharp.chm

2003 - Peachpit - C Sharp Web Development With Asp Net, Visual Quickstart Guide.chm

2003 - Sams - Ms© Visual C Sharp Net 2003 Developer's Cookbook.chm

2003 - Sybex - C Sharp Complete.chm

2003 - Sybex - C Sharp Network Programming.chm

2004 - Apress - C Sharp Threading Handbook.chm

2004 - Ms - C Sharp Programmer's Cookbook.chm

2004 - O'reilly - C Sharp Cookbook.chm

2004 - Wiley - Wrox - Beginning Asp.Net 1.1 With Visual C Sharp.Net 2003.pdf

2004 - Wiley - Wrox - Professional CSharp 3rd Edition.rar

2005 - Apress - Pro C Sharp 2005 And The .Net 2.0 Platform 3rd Edition.pdf

2005 - Ph - Core C Sharp And Net.chm

2005 - Wiley - CSharp 2005 For Dummies.rar

2005 - Wiley - Professional .NET 2.0 Generics.pdf

2006 - Apress - Beginning Asp.Net 2.0 In C Sharp 2005 From Novice To Professional.pdf

2006 - Aw - Applying Domain-Driven Design And Patterns - With Examples In C Sharp And .Net.chm

2006 - Aw - Essential C Sharp V2 0.chm

2006 - AW - Hitchhiker's Guide to Visual Studio and SQL Server, 7th Edition - Best Practice Architectures and Examples.chm

2006 - O'Reilly - C Sharp Cookbook, 2nd Edition.chm

2006 - Wiley - Beginning Visual C Sharp 2005.chm

2006 - Wiley - Beginning C Sharp 2005 Databases.pdf

2006 - Wiley - Wrox - Visual C Sharp 2005 Express Edition Starter Kit.pdf

70-305 70-315 Developing Web Applications With Visual Basic Net And Visual C Sharp Net - 2002.chm

70-316 Testking.Developing.Windows.Applications.With.C Sharp(Ver 2.0).pdf

Addison Wesley - C Sharp Design Patterns 301-424.pdf

Addison Wesley - Graphics Programming With C Sharp And Gdi+.pdf

Apress - A Programmer's Guide To Ado Net In C Sharp.pdf

Apress - Beginning ASP .NET 2.0 E-Commerce in C# 2005 - From Novice to Professional. 2005.pdf

Apress - C Sharp And The .Net Platform, 2nd Edition.pdf

Apress - C Sharp Class Design Handbook Coding Effective Classes (2003).chm

Apress - C Sharp Programmers Handbook (2004).chm

Apress - Database Programing With C Sharp.pdf

Apress - Dissecting A C Sharp Application Inside Sharpdevelop (2004).pdf

Apress - Net User Interfaces With C Sharp.chm

Apress - Pro Asp.Net 2.0 In C Sharp.pdf

Apress - Winform - Data Entry And Validation With C Sharp And Vb Net Windows Forms 2003.chm

Apress.Accelerated.C.Sharp.2005.Aug.2006.pdf

Apress.Beginning.Asp.Net.2.0.E.Commerce.In.C.Sharp.2005.From.Novice.To.Professional.Oct.2005.pdf

Asp Net Website Programming, C Sharp.chm

Asp.Net - C Sharp.pdf

Aw - 2003 - Windows Forms Programming In C Sharp.chm

Aw - 2004 - Effective C Sharp 50 Specific Ways To Improve.chm

Aw - Net Compact Framework Programming With C Sharp.chm

Beginning Asp Net 1.1 With Visual C Sharp Net 2003 (2004).pdf

Beginning C Sharp Objects - From Concepts To Code (Apress, 2004).chm

Bruce Eckel & Larry O'brien - Thinking In C Sharp.pdf

Building An Online Shopping Cart Using C Sharp And Asp Net Part 1.pdf

Building An Online Shopping Cart Using C Sharp Part 2.pdf

C Sharp - Introduction To Design Pattern In C Sharp Vol_3 - Ibm.pdf

C Sharp 2.0 Practical Guide For Programmers.pdf

C Sharp And The .Net Platform.pdf

C Sharp Developer's Guide To Asp Net, Xml, And Ado Net.pdf

C Sharp Developer's Headstart [Mcgraw-Hill, 2001, 0-07-219108-2].pdf

C Sharp Essentials 2nd O'reilly 2001.chm

C Sharp Network Programming.chm

C Sharp.Network.Programming.pdf

C Sharp.Vb.Net.Ms Press - Oop With Microsoft Vb.Net And C Sharp Step By Step.pdf

Computing With C Sharp And The Net Framework 2003.chm

Correctexams Mcsd 070-320 Exam Xml Web Services And Server Components With C Sharp.Net V1-2003.pdf

Correctexams Microsoft 70-315 Mcsd Mcad Develop & Implement Web Apps With C Sharp Edt6.pdf

Creating Custom Net Controls With C Sharp.pdf

Data Structures And Algorithms With Object-Oriented Design Patterns In C Sharp.pdf

Developing A Universal Data Access Layer Leveraging Ado.Net, C Sharp And Factory Design Pattern.pdf

Developing And Implementing Web Applications With Visual C Sharp Net And Visual Studio Net Exam Cram 2 (Exam 70-315).chm

Dissecting A C Sharp Application.pdf

Distributed Net Programming In C Sharp.chm

Dot Net Remoting - [Ms Press] - Ms Net Remoting - (2003) - (Code Samples In C-Sharp).chm

Exam 070-320 - Mcsd Mcad - Xml Webservices And Server Components With C Sharp .Net (V 6.0).pdf

Expert C Sharp 2005 Business Objects, 2nd Edition (2006).pdf

For Dummies - Visual Studio .Net C Sharp For Dummies Quick Reference Guide.pdf

Gdi Programming - Creating Custom Controls Using C Sharp.pdf

Introduction To 3d Game Engine Design Using Directx 9 And C Sharp.chm

Introduction To C Sharp Programming For The Microsoft .Net Platform.pdf

Learning C Sharp 2005, 2nd Edition (2006).chm

Manning - Windows Forms Programming With C Sharp.pdf

Mastering Asp.Net With C Sharp.pdf

Mastering C Sharp Database Programming - Sybex.pdf

Mastering C Sharp Database Programming.chm

Mcad Mcsd 70-305,70-315 Developing Web Apps With Vb Net & Visual C Sharp Net, 2nd Ed.chm

Mcad Mcsd 70-306,70-316 Developing Windows-Based Apps With Vb Net & Visual C Sharp Net, 2nd Ed.chm

Mcad Mcsd 70-310,70-320 Developing Xml Web Services & Server Components With Vb Net & Visual C Sharp Net.chm

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Part 1
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Part 7
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Part 15

AJAX VIDEOTUTORIALES DOWNLOAD

2011-03-16T14:34:00.002+05:30

ALL WINDOWS SERVER 2008 COLLECTION E-BOOKS

2011-03-16T14:26:00.000+05:30

Collection of 50 ebooks about Windows Server 2008

English | PDF, CHM, RAR, ZIP | 1.25 GB
List of these ebooks is below.

Addison Wesley - The Complete Guide to Windows Server 2008 (2008).pdf

McGraw-Hill - Microsoft Windows Server 2008 Administration (2008).pdf

McGraw-Hill - Microsoft Windows Server 2008, A Beginner s Guide (2008).pdf

McGraw-Hill - Microsoft Windows Server 2008, The Complete Reference (2008).pdf

MS Press - Introducing Windows Server 2008 (2007).chm

MS Press - MCTS Self Paced Training Kit Exam 70-640 Configuring Windows Server 2008 Active Directory (2008).pdf

MS Press - MCTS Self Paced Training Kit Exam 70-642 Configuring Windows Server 2008 Network Infrastructure (2008).pdf

...

MS Press - Transitioning Your MCSA-MCSE To Windows Server 2008 (2009).pdf

MS Press - Windows Server 2008 Active Directory Resource Kit (2008).pdf

MS Press - Windows Server 2008 Inside Out (2008).pdf

MS Press - Windows Server 2008 Networking and Network Access Protection (NAP) (2008).pdf

MS Press - Windows Server 2008 PKI and Certificate Security (2008).pdf

MS Press - Windows Server 2008 Security Resource Kit (2008).pdf

MS Press - Windows Server 2008 Server Core Administrator s Pocket Consultant (2008).chm

MS Press - Windows Server 2008 TCP-IP Protocols and Services (2008).pdf

MS Press - Windows Server 2008 Terminal Services Resource Kit (2008).chm

MS Press - Windows Small Business Server 2008 Administrator s Companion (2009).pdf

O Reilly - Windows Server 2008, The Definitive Guide (2008).chm

Packt - Small Business Server 2008 - Installation, Migration, and Configuration (2009).pdf

Sams - Teach Yourself Windows Server 2008 in 24 Hours (2008).chm

Sams - Windows Server 2008 Hyper-V Unleashed (2008).pdf

Sams - Windows Server 2008 Unleashed (2008).pdf

SkillSoft Courseware - Active Directory Certificate Services in Windows Server 2008.zip

SkillSoft Courseware - Active Directory Objects in Windows Server 2008.zip

SkillSoft Courseware - Communications and Security in Windows Server 2008.zip

SkillSoft Courseware - Configuring DNS in Windows Server 2008.zip

SkillSoft Courseware - Group Policy Objects Strategy in Windows Server 2008.zip

SkillSoft Courseware - Monitoring Backups and Recovery in Windows Server 2008.zip

Sybex - Administering Windows Server 2008 Server Core (2008).pdf

Sybex - Mastering Active Directory for Windows Server 2008 (2008).pdf

Sybex - MCITP Windows Server 2008 Server Administrator Study Guide Exam 70-646 (2008).pdf

Sybex - MCITP, Windows Server 2008 Enterprise Administrator Study Guide (2009).pdf

Sybex - MCITP, Windows Server 2008 Server Administrator Study Guide (2008).pdf

Sybex - MCTS Windows Server 2008 Active Directory Configuration Exam Study Guide (2008).pdf

Sybex - MCTS, Windows Server 2008 Applications Infrastructure Configuration Study Guide (2008).pdf

Sybex - Windows Server 2008 Hyper-V (2009).pdf

Syngress - Securing Windows Server 2008 (2008).pdf

Syngress - The Real MCTS-MCITP Upgrading Your MCSA on Windows Server 2003 to Windows Server 2008 Exam 70-648 Prep Kit (2008).pdf

Syngress - The Real MCTS-MCITP Upgrading Your MCSE on Windows Server 2003 to Windows Server 2008 Exam 70-649 Prep Kit (2008).pdf

Syngress - The Real MCTS-MCITP Windows Server 2008 Configuring Active Directory Exam 70-640 Prep Kit (2008).pdf

Syngress - The Real MCTS-MCITP Windows Server 2008 Configuring Applications Infrastructure Exam 70-643 Prep Kit (2008).pdf

Syngress - The Real MCTS-MCITP Windows Server 2008 Configuring Network Infrastructure Exam 70-642 Prep Kit (2008).pdf

Syngress - The Real MCTS-MCITP Windows Server 2008 Enterprise Administrator Exam 70-647 Prep Kit (2008).pdf

Syngress - The Real MCTS-MCITP Windows Server 2008 Server Administrator Exam 70-646 Prep Kit (2008).pdf

Wiley - Windows Server 2008 Active Directory Configuration with Virtual Lab (2009).pdf

Wiley - Windows Server 2008 All-In-One Desk Reference For Dummies (2008).pdf

Wiley - Windows Server 2008 Bible (2008).pdf

Wiley - Windows Server 2008 For Dummies (2008).pdf

Wiley - Windows Server 2008 Network Infrastructure Configuration (2008).pdf

Windows Server 2008 Resource Kit CD.rar

Download Links:
http://www.fileserve.com/file/Ex9DqEt/Windows_Server_2008_ebook_collection.part01.rar

http://www.fileserve.com/file/u9MjZJf/Windows_Server_2008_ebook_collection.part02.rar

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http://www.fileserve.com/file/4ZrDxJU/Windows_Server_2008_ebook_collection.part08.rar

http://www.fileserve.com/file/ZECcNHm/Windows_Server_2008_ebook_collection.part09.rar

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http://www.fileserve.com/file/D9m55y3/Windows_Server_2008_ebook_collection.part12.rar

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TOP TEN ERRORS JAVA PROGRAMMERS MAKE

2011-03-16T14:25:00.000+05:30

Whether you program regularly in Java, and know it like the back of your hand, or whether you're new to the language or a casual programmer, you'll make mistakes. It's natural, it's human, and guess what? You'll more than likely make the same mistakes that others do, over and over again. Here's my top ten list of errors that we all seem to make at one time or another, how to spot them, and how to fix them.

10. Accessing non-static member variables from static methods (such as main)

Many programmers, particularly when first introduced to Java, have problems with accessing member variables from their main method. The method signature for main is marked static - meaning that we don't need to create an instance of the class to invoke the main method. For example, a Java Virtual Machine (JVM) could call the class MyApplication like this :-

MyApplication.main ( command_line_args );

This means, however, that there isn't an instance of MyApplication - it doesn't have any member variables to access! Take for example the following application, which will generate a compiler error message.

public class StaticDemo
{
public String my_member_variable = "somedata";
public static void main (String args[])
{
// Access a non-static member from static method
System.out.println ("This generates a compiler error" +
my_member_variable );
}
}

If you want to access its member variables from a non-static method (like main), you must create an instance of the object. Here's a simple example of how to correctly write code to access non-static member variables, by first creating an instance of the object.

public class NonStaticDemo
{
public String my_member_variable = "somedata";

public static void main (String args[])
{
NonStaticDemo demo = new NonStaticDemo();

// Access member variable of demo
System.out.println ("This WON'T generate an error" +
demo.my_member_variable );
}
}

9. Mistyping the name of a method when overriding
Overriding allows programmers to replace a method's implementation with new code. Overriding is a handy feature, and most OO programmers make heavy use of it. If you use the AWT 1.1 event handling model, you'll often override listener implementations to provide custom functionality. One easy trap to fall into with overriding, is to mistype the method name. If you mistype the name, you're no longer overriding a method - you're creating an entirely new method, but with the same parameter and return type.

public class MyWindowListener extends WindowAdapter {
// This should be WindowClosed
public void WindowClose(WindowEvent e) {
// Exit when user closes window
System.exit(0);
}
});

Compilers won't pick up on this one, and the problem can be quite frustrating to detect. In the past, I've looked at a method, believed that it was being called, and taken ages to spot the problem. The symptom of this error will be that your code isn't being called, or you think the method has skipped over its code. The only way to ever be certain is to add a println statement, to record a message in a log file, or to use good trace debugger (like Visual J++ or Borland JBuilder) and step through line by line. If your method still isn't being called, then it's likely you've mistyped the name.

8. Comparison assignment ( = rather than == )
This is an easy error to make. If you're used other languages before, such as Pascal, you'll realize just how poor a choice this was by the language's designers. In Pascal, for example, we use the := operator for assignment, and leave = for comparison. This looks like a throwback to C/C++, from which Java draws its roots.

Fortunately, even if you don't spot this one by looking at code on the screen, your compiler will. Most commonly, it will report an error message like this : "Can't convert xxx to boolean", where xxx is a Java type that you're assigning instead of comparing.

7. Comparing two objects ( == instead of .equals)
When we use the == operator, we are actually comparing two object references, to see if they point to the same object. We cannot compare, for example, two strings for equality, using the == operator. We must instead use the .equals method, which is a method inherited by all classes from java.lang.Object.

Here's the correct way to compare two strings.

String abc = "abc"; String def = "def";

// Bad way
if ( (abc + def) == "abcdef" )
{
......
}
// Good way
if ( (abc + def).equals("abcdef") )
{
.....
}

6. Confusion over passing by value, and passing by reference
This can be a frustrating problem to diagnose, because when you look at the code, you might be sure that its passing by reference, but find that its actually being passed by value. Java uses both, so you need to understand when you're passing by value, and when you're passing by reference.

When you pass a primitive data type, such as a char, int, float, or double, to a function then you are passing by value. That means that a copy of the data type is duplicated, and passed to the function. If the function chooses to modify that value, it will be modifying the copy only. Once the function finishes, and control is returned to the returning function, the "real" variable will be untouched, and no changes will have been saved. If you need to modify a primitive data type, make it a return value for a function, or wrap it inside an object.

When you pass a Java object, such as an array, a vector, or a string, to a function then you are passing by reference. Yes - a String is actually an object, not a primitive data type. So that means that if you pass an object to a function, you are passing a reference to it, not a duplicate. Any changes you make to the object's member variables will be permanent - which can be either good or bad, depending on whether this was what you intended.

On a side note, since String contains no methods to modify its contents, you might as well be passing by value.

5. Writing blank exception handlers
I know it's very tempting to write blank exception handlers, and to just ignore errors. But if you run into problems, and haven't written any error messages, it becomes almost impossible to find out the cause of the error. Even the simplest exception handler can be of benefit. For example, put a try { .. } catch Exception around your code, to catch ANY type of exception, and print out the message. You don't need to write a custom handler for every exception (though this is still good programming practice). Don't ever leave it blank, or you won't know what's happening.

For example

public static void main(String args[])
{
try {
// Your code goes here..
}
catch (Exception e)
{
System.out.println ("Err - " + e );
}
}

4. Forgetting that Java is zero-indexed
If you've come from a C/C++ background, you may not find this quite as much a problem as those who have used other languages. In Java, arrays are zero-indexed, meaning that the first element's index is actually 0. Confused? Let's look at a quick example.

// Create an array of three strings
String[] strArray = new String[3];

// First element's index is actually 0
strArray[0] = "First string";

// Second element's index is actually 1
strArray[1] = "Second string";

// Final element's index is actually 2
strArray[2] = "Third and final string";

In this example, we have an array of three strings, but to access elements of the array we actually subtract one. Now, if we were to try and access strArray[3], we'd be accessing the fourth element. This will case an ArrayOutOfBoundsException to be thrown - the most obvious sign of forgetting the zero-indexing rule.

Other areas where zero-indexing can get you into trouble is with strings. Suppose you wanted to get a character at a particular offset within a string. Using the String.charAt(int) function you can look this information up - but under Java, the String class is also zero-indexed. That means than the first character is at offset 0, and second at offset 1. You can run into some very frustrating problems unless you are aware of this - particularly if you write applications with heavy string processing. You can be working on the wrong character, and also throw exceptions at run-time. Just like the ArrayOutOfBoundsException, there is a string equivalent. Accessing beyond the bounds of a String will cause a StringIndexOutOfBoundsException to be thrown, as demonstrated by this example.

public class StrDemo
{
public static void main (String args[])
{
String abc = "abc";

System.out.println ("Char at offset 0 : " + abc.charAt(0) );
System.out.println ("Char at offset 1 : " + abc.charAt(1) );
System.out.println ("Char at offset 2 : " + abc.charAt(2) );

// This line should throw a StringIndexOutOfBoundsException
System.out.println ("Char at offset 3 : " + abc.charAt(3) );
}
}

Note too, that zero-indexing doesn't just apply to arrays, or to Strings. Other parts of Java are also indexed, but not always consistently. The java.util.Date, and java.util.Calendar classes start their months with 0, but days start normally with 1. This problem is demonstrated by the following application.

import java.util.Date;
import java.util.Calendar;

public class ZeroIndexedDate
{
public static void main (String args[])
{
// Get today's date
Date today = new Date();

// Print return value of getMonth
System.out.println ("Date.getMonth() returns : " +
today.getMonth());

// Get today's date using a Calendar
Calendar rightNow = Calendar.getInstance();

// Print return value of get ( Calendar.MONTH )
System.out.println ("Calendar.get (month) returns : " +
rightNow.get ( Calendar.MONTH ));
}
}

Zero-indexing is only a problem if you don't realize that its occurring. If you think you're running into a problem, always consult your API documentation.

3. Preventing concurrent access to shared variables by threads
When writing multi-threaded applications, many programmers (myself included) often cut corners, and leave their applications and applets vulnerable to thread conflicts. When two or more threads access the same data concurrently, there exists the possibility (and Murphy's law holding, the probability) that two threads will access or modify the same data at the same time. Don't be fooled into thinking that such problems won't occur on single-threaded processors. While accessing some data (performing a read), your thread may be suspended, and another thread scheduled. It writes its data, which is then overwritten when the first thread makes its changes.

Such problems are not just limited to multi-threaded applications or applets. If you write Java APIs, or JavaBeans, then your code may not be thread-safe. Even if you never write a single application that uses threads, people that use your code WILL. For the sanity of others, if not yourself, you should always take precautions to prevent concurrent access to shared data.

How can this problem be solved? The simplest method is to make your variables private (but you do that already, right?) and to use synchronized accessor methods. Accessor methods allow access to private member variables, but in a controlled manner. Take the following accessor methods, which provide a safe way to change the value of a counter.

public class MyCounter
{
private int count = 0; // count starts at zero

public synchronized void setCount(int amount)
{
count = amount;
}

public synchronized int getCount()
{
return count;
}
}
2. Capitalization errors
This is one of the most frequent errors that we all make. It's so simple to do, and sometimes one can look at an uncapitalized variable or method and still not spot the problem. I myself have often been puzzled by these errors, because I recognize that the method or variable does exist, but don't spot the lack of capitalization.

While there's no silver bullet for detecting this error, you can easily train yourself to make less of them. There's a very simple trick you can learn :-

all methods and member variables in the Java API begin with lowercase letters
all methods and member variables use capitalization where a new word begins e.g - getDoubleValue()
If you use this pattern for all of your member variables and classes, and then make a conscious effort to get it right, you can gradually reduce the number of mistakes you'll make. It may take a while, but it can save some serious head scratching in the future.

1. Null pointers!

Null pointers are one of the most common errors that Java programmers make. Compilers can't check this one for you - it will only surface at runtime, and if you don't discover it, your users certainly will.

When an attempt to access an object is made, and the reference to that object is null, a NullPointerException will be thrown. The cause of null pointers can be varied, but generally it means that either you haven't initialized an object, or you haven't checked the return value of a function.

Many functions return null to indicate an error condition - but unless you check your return values, you'll never know what's happening. Since the cause is an error condition, normal testing may not pick it up - which means that your users will end up discovering the problem for you. If the API function indicates that null may be returned, be sure to check this before using the object reference!

Another cause is where your initialization has been sloppy, or where it is conditional. For example, examine the following code, and see if you can spot the problem.

public static void main(String args[])
{
// Accept up to 3 parameters
String[] list = new String[3];

int index = 0;

while ( (index < args.length) && ( index < 3 ) )
{
list[index++] = args[index];
}

// Check all the parameters
for (int i = 0; i < list.length; i++)
{
if (list[i].equals "-help")
{
// .........
}
else
if (list[i].equals "-cp")
{
// .........
}
// else .....
}
}
This code (while a contrived example), shows a common mistake. Under some circumstances, where the user enters three or more parameters, the code will run fine. If no parameters are entered, you'll get a NullPointerException at runtime. Sometimes your variables (the array of strings) will be initialized, and other times they won't. One easy solution is to check BEFORE you attempt to access a variable in an array that it is not equal to null.

Summary
These errors represent but some of the many that we all make. Though it is impossible to completely eliminate errors from the coding process, with care and practice you can avoid repeating the same ones. Rest assured, however, that all Java programmers encounter the same sorts of problems. It's comforting to know, that while you work late into the night tracking down an error, someone, somewhere, sometime, will make the same mistake!

We'd like to thank the readers of the comp.lang.java.programmer newsgroup for their suggestions for the top ten. Regrettably, due to the number of submissions, not every error could be featured - but we think this "Top Ten" list represents the most popular and frequent errors people make.

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Blogs Rater

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Blogs Rater is a free blog directory where you can submit your website / blog and have people rate your website to gain more backlinks, exposure and traffic. You do not need to register before you submit your blog.

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E-Articles

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E-Articles is a human-reviewed free article submission directory where you can submit your original articles and tutorials to boost specific keywords for SEO purposes, to generate links pointing back to your site and also to establish yourself as a trusted source on a matter of your interest. Each submitted article is automatically translated into 16 foreign languages and proofread. Registration is required.

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Million Blogs Online

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Million Blogs Online is a free submission directory where you can find listings of relevant blogs to match your interests and where you can also submit your website to obtain more traffic and exposure. Registration is not mandatory.

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PaidDirectory

http://www.paiddirectory.com/

PaidDirectory is a paid submission directory where you can submit your website and browse other resources organized per specific category. Registration is not required to submit your site. There are several pricing options (starting from $3.50/year) that you can check on the submission page. Depending on the pricing level you choose, you can aslo submit your RSS feed to the directory.

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BlogDirectory.org.uk

http://www.blogdirectory.org.uk/

BlogDirectory.org.uk is a paid quality blog directory that allows you to submit your blog and to discover other interesting blog sites categorized per topic covered. Registration is not required to submit your blog. There are two types of submission available: Featured (£10/one year) and Regular (£5/lifetime).

To submit your site to BlogDirectory.org.uk, provide the title and URL of your blog, along with the URL of your RSS feed and a short description of your blog content. Then type in your email and name and select a category for your blog. Optionally, you can also provide some location references to have a Google map featured in your blog page inside the blog directory.

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Bllogs

http://www.blloggs.com/

Bllogs is a free human-reviewed blog directory that allows you to submit your url to promote the content of your blog to a wider audience. Bllogs comprises blogs coming from all over the world and written in multiple languages on different topics. Registration is not mandatory.

To submit your blog to Bllogs, just provide the title and URL of your website, the URL of your RSS feed and a brief description for your blog. You also need to select the language of your blog, since Bllogs allows you to submit a website in a wide variety of languages. Last, add your name and e-mail address.

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PlanetUSA

http://www.planetusa.us/

PlanetUSA is a free blog directory, search engine and business catalog specifically devoted to US enterprises where you can submit your website or blog to obtain more visibility and backlinks for your company website. You can also discover other companies you might be interested in by browsing through the categories, search in alphabetical order or by cities. Registration is not mandatory to submit your site.

To submit your website / blog to PlanetUSA, you need to add the title and URL of your blog. Then, write a description for it and select an appropriate category. You also need to choose the state and city of where your company is located. Last, provide your name and email address to finish the submission process.

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LazyBlogDirectory

http://lazyblogdirectory.com/

LazyBlogDirectory is a human-edited blog directory that allows you to submit your website and articles to receive inbound links and obtain more exposure for your content. Three submission plans are available: Regular with reciprocal links (free), Regular ($2/lifetime) and Featured ($5/year). Payment is permitted via PayPal only. Registration is not mandatory.

To submit your blog to LazyBlogDirectory, first you need to choose a pricing plan. Then, add a title and URL of your blog (adding a description is optional). Also as an option, you can leverage the visibility of your website by including metakeywords and metadescriptions. Last, provide your name and email address.

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BlogoWogo

http://www.blogowogo.com/

BlogoWogo is a free blog directory and blog aggregator where you can submit your website and have people rate your content to gain more exposure and traffic. You need to register before you submit your blog.

To add a website to BlogoWogo, you first need to register. Then add the title, URL and RSS feed of your blog. Last, choose a category for your blog, and you're set.

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Blogs All Over the World

http://www.blogsallovertheworld.com/

Blogs All Over the World is a free human-reviewed blog directory which features blogs and websites from every corner of the planet that belong to a large range of categories. You can use this list to submit a website / blog and win more exposure. Vistors can also rate and comment on every website inside the directory to share their feedback. Registration is not mandatory to go through the submission process.

To submit your blog to Blogs All Over the World, you need to provide the title, URL and a description for your blog. You also have to add a reciprocal link URL and your e-mail address.

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Free RSS and Link Directory

http://www.rss-directory.us/

Free RSS and Link Directory is a non-paid submission directory where you can submit your website or blog to gain more exposure for your content and also increase your traffic. registration is not required. there are three submission plans available: Free, 1 Year (€5), 3 Years (€10), Lifetime (€30).

To add a website to Free RSS and Link Directory, just type the URL of your site / blog and the service will automatically extract the metadata from your pages. Then, edit the metadata accordingly, pick a category where your website content fits in, add your email address and last select a submission plan to get listed inside the directory.

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Blogoculars

http://www.blogoculars.com/

Blogoculars is a free blog directory and social community related to blogging matters where not only you can discover interesting content, but you can also submit your blog to showcase your best articles and obtain more traffic. Inside Blogoculars you can also find an online forum dedicated to blogging topics (registration is requested to post).

To add a website to Blogoculars, you first need to sign-up. Then, click on the "Add Blog" button and provide the feed URL of your blog. Blogoculars will check its existence and retrieve its metadata (name, blog URL and description) automatically. Last, check whether the imported data from your feed is correct and choose a category for your blog to get listed inside the directory.

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Everything Directory for Blogs

http://directory.everything-fine.info/index.php

Everything Directory for Blogs is a blog directory where you can discover new content sources and also where you can submit your blog url and your best articles to get further visibility and baclinks. There are three options for blog submissions: Regular with reciprocal links (free), Regular ($5/year) and Featured ($12/lifetime). Registration is mandatory.

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http://puppyurl.com/

PuppyURL is a human-edited SEO friendly blog directory where you can submit a website URL to receive inbound links, more traffic and gain more visibility. There are two options available to submit your website to PuupyURL: Regular (free) and Featured ($5.90/year). Registration is not required.

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http://www.kahuki.com/

Kahuki is a manually-reviewed blog directory where you can add a website to get further content exposure and traffic. You can choose between two website submission options: Regular ($9.95/year) and Featured ($19.95/year). Registration is not mandatory.

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ArticlesXpert is a free article submission directory where you can have your best articles featured with a link back to your website to get more traffic. The topics of the articles you can submit span from marketing, to automotive, from sports to technology and many other categories. Registration is mandatory.

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Article Directory

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Article Directory is a free article submission directory where you can submit and promote your best articles to gain backlinks and exposure for your blog or website. Registration is mandatory to submit your articles and the submission process is manually-reviewed.

To submit your articles to Article Directory, you first need to log in. Then just add the title, URL, author and brief description of your article.

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Blog Toplist

http://www.blogtoplist.com/

Blog Toplist is a human-reviewed blog directory where you can promote the content of your blog to a wider audience to gain backlinks and traffic. You can submit both the URL of your blog and your RSS feed. Registration is mandatory.

To submit your blog to Blog Toplist, you first have to place a button with a reciprocal link to Blog Toplist on your website / blog. Then head to the submission page, provide your registration credentials and add the usual information about your website (title, URL, description, etc.).

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Posted on January 24, 2011

Malatya

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Malatya is a free RSS directory where you can submit your website RSS feed to obtain more traffic and exposure for your content. Registration is not mandatory to use the service. After you submit your RSS feed, the editors at Malatya will manually check your feed before displaying your content inside the directory.

To submit your RSS feed to Malatya, please choose a relevant category that describes your blog content and then enter the URL of your RSS feed.

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Posted on January 26, 2011

Fwisp

http://fwisp.com/

Fwisp is a crowdsourced submission directory where users can discover, share submit and rate articles, news and videos gathered from the web. Content producers can leverage Fwisp to attract more traffic and backlinks to their websites. The main focus of the site is on economics, business and finance. Registration is mandatory to submit content, but you can login also with your Facebook or Twitter credentials.

To submit your articles to Fwisp, provide the URL of your blog / website, the specific title and URL of the article, news or video you want to share, select a relevant category and then write a brief description for your content.

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Posted on January 22, 2011

FeedoOyoo

http://www.feedooyoo.com/

FeedoOyoo is a free RSS directory and an RSS search engine that allows you to submit your RSS feed to gain more visibility and attract a larger audience to your website. Registration is not mandatory and FeedoOyoo is not human-reviewed.

To submit your RSS feed to FeedoOyoo, just enter the feed URL of your blog and write an appropriate set of tags to describe your site. After you submit your feed, your blog shows up immediately inside the FeedoOyoo directory and anyone can reach your web site via a direct link or by downloading the content of your site as a PDF file.

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Posted on January 20, 2011

Society of Socialpreneurs

http://www.societyofsocialpreneurs.com/blogdirectory.html

Society of Socialpreneurs is a blog directory and social business network where you can submit your website or blog and get more exposure. The blog submission process is free as long as you place a button with a reciprocal link promoting the directory on your own website. Registration is not mandatory.

To submit your blog to Society of Socialpreneurs, after you post their button on your website, just provide your name and e-mail address, the title and URL of your blog and write a description for your blog.

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Posted on January 19, 2011

Search 4 Blog

http://www.search4blog.com/

Search 4 Blog is a paid blog directory where you can submit the URL of your blog site as well as individual blog articles you publish in order to get more visibility. Three submission plans are available: Regular with reciprocal links (free), Regular links ($5/one month) and Featured ($10/one month). Registration is not mandatory to submit your website, but you do need to register to submit individual articles.

To submit your blog to Search 4 Blog, first select a pricing plan. Then, add the title and URL of your blog. Last, enter your name and email address and choose an appropriate category for your blog.

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Posted on January 17, 2011

Wutzle

http://www.wutzle.com/

Wutzle is both a free blog directory and a blog search engine where you can find relevant blogs that match your interests and also submit your website to get more traffic and exposure. You need to register to use Wutzle and you can submit up to three websites.

To submit your blog to Wutzle, you need to add the URL, the title and a description of your blog. Then, grab the HTML code for the Wutzle logo and rating link (which allows readers to rate your site and increase its ranking inside Wutzle) and paste it on your website.

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Delightfulblogs

http://www.delightfulblogs.com/

Delightfulblogs is a human-reviewed blog directory where you can promote your blog to get more traffic. There are two URL submission options available: Regular ($15/one-time fee) and Featured ($45/three months + one free month). The Featured option allows to have your website displayed at the top of the category page and also to have your site featured from time to time on the homepage of the directory. Please note that Delightfulblogs lets you submit your blog only if it is at least three-month old.

To submit your site to Delightfulblogs, first choose a submission plan. Then, enter the name and URL of your blog, select an appropriate category and write a brief description for your blog. Last, provide your name and email address.

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Posted on January 13, 2011

RSSFeeds.org

http://www.rssfeeds.org/

RSSFeed.org is an RSS directory where you can submit the URL of your website or blog RSS feed to receive inbound links, more traffic and gain more visibility for your original content. You can submit either RSS or ATOM feeds and no registration is requested to add your RSS feed to the directory.

To submit your RSS feed to RSSFeeds.org, send an email message with your feed title, URL, a brief description and a suggested category to rssdirectory@usguides.net.

Click here to submit your RSS feed to RSSFeeds.org.

Posted on January 11, 2011

Anatech.NET

http://anatech.net/

Anatech.NET is an RSS directory where you can promote your own website and get more traffic. Three submission options are available: Free, 1 Year ($5), 3 Years ($10), Lifetime ($30). Only paid submissions allow you to have your website featured on the homepage of Anatech.NET.

To submit your RSS feed to Anatech.NET, just provide the url of your website and the system will automatically extract the metadata of your site (title and description). Then you can edit the info provided, add a category, your email address and then submit the RSS feed of your website.

Click here to submit your RSS feed to Anatech.NET.

Posted on January 3, 2011

AddYourBlog.Com

http://www.addyourblog.com/

AddYourBlog.Com is a free blog directory where you can promote your blog and receive more traffic. You can also submit your regular website, as long as your site has a blog in it and you link specifically the blog. For your blog url to be added to the directory you must provide a link back to AddYourBlog.Com on your own blog.

To submit your blog to AddYourBlog.Com, first copy the reciprocal link on your blog. Then choose a category where your blog content best fits in and provide the title and URL of your blog. Last, add a description, provide the RSS feed url of your blog, your email and a set of relevant tags.

Click here to submit your blog to AddYourBlog.Com.

Posted on December 31, 2010

EZE

http://www.ezedir.com/

EZE is a free, human-reviewed website directory where you can submit the URL of your website to gain more exposure for your content and reach a wider audience. EZE also provides an automatic submission tool that allows you to submit your site to multiple search engines and RSS directories in one shot.

To submit your website URL to EZE, first provide your name, email address and website URL. Then add the title of your website, write a brief description, add your geographic location and (optionally) provide additional info about your site. The category where your website belongs will be manually chosen by EZE editor during the review process.

Click here to submit your website URL to EZE.

Posted on December 27, 2010

DirectoryBlogs

http://www.directoryblogs.com/

DirectoryBlogs is a human-edited blog directory where you can find a selection of blog sites related to business. All submitted blogs are divided in categories and ranked for their PageRank value. Multiple submission options (paid and free) are available for you to submit your own business-related blog site and gain greater exposure.

To submit your blog to DirectoryBlogs, first choose your pricing plan. Then click on "Get Your List" and provide the following info: name, company, email, website, category, title and description.

Click here to add your blog to DirectoryBlogs.

Posted on December 22, 2010

Quick Blog Directory

http://www.quickblogdirectory.com/

Quick Blog Directory is a blog directory where you can showcase your blog site to get more visibility. All submitted blogs are featured on the homepage, where there is also a list of the top blogs rated by the users of the directory. No registration to Quick Blog Directory is needed to submit your blog to the directory.

To submit your blog to Quick Blog Directory, provide first the title and URL of your blog, then select your country and the category your blog content belongs to and, last, write a brief description of your blog site.

Click here to add your blog to Quick Blog Directory.

Posted on December 20, 2010

BlogRateDirectory

http://www.blogratedirectory.com/

BlogRateDirectory is a comprehensive blog directory which is already counting more than 5,500 blog submissions and you too can add your own blog site to get more exposure for your content. BlogRateDirectory also provides a list of tools like blogging platforms, search engines and feed readers. You are not required to register to submit your blog to the directory.

To submit your blog to BlogRateDirectory, you only need to provide the full URL of your blog and your own email address.

Click here to add your blog to BlogRateDirectory.

Posted on December 16, 2010

BlogZoop

http://blogzoop.com/

BlogZoop is a blog directory where you can submit the url of your blog to promote your own content. BlogZoop also provides a selection of free themes to style your blog site and an online tool to check your PageRank, Alexa Rank and backlinks. Registration is not mandatory to submit your blog to the directory.

To add your blog to BlogZoop, provide the title and URL of your blog and write a brief description. Then type in the META keywords and META description of your blog, add your name and email, select a category and provide the link of the reciprocal URL which you need to place on your site to have your blog added to the directory.

Click here to add your blog to BlogZoop.

Posted on December 15, 2010

TopWeblogDirectory

http://topweblogdirectory.com/

TopWeblogDirectory is a blog directory where you can submit your own blog to promote your content. Registration is not mandatory to submit your blog, but it is required to comment or rate other blogs featured inside the directory. There are three types of options to submit your URLs: Link With Reciprocal (Free), Regular Link ($6 / one-time), Featured Link ($13 / one-time).

To add your blog to BlogRank, first choose the type of submission you prefer. Then provide the title and URL of your blog, select a category, add a description, type in the META keywords and description of your blog and add blog owner name and email.

Click here to add your blog to TopWeblogDirectory.

Posted on December 13, 2010

Pingates

http://pingates.com/

Pingates is not a blog directory nor an RSS directory where you can submit your website. What Pingates does is send a "ping", a notification, to a handful of sites alerting them that your blog has been updated. Then, the web crawlers of these websites can come by and notify their readers of the update. No registration is needed.

To ping your blog using Pingates, simply type the title and url of your blog, select the sites you want to send a ping to (you can also check all of them with a single button) and then click on "Send pings".

Posted on December 11, 2010

Blogs Rating

http://www.blogsrating.com/

Blogs Rating is a free blog directory where you can submit your website url to gain maximum exposure for your content. Registration is not mandatory to submit your content to Blogs Rating, but you need to provide a link back to the site by using either a regular URL or a widget button. All blogs submitted to Blogs rating are human-reviewed.

To submit your blog to Blogs Rating, first you need to post a link to the service on your website. Then, add the URL of your blog, the link back to Blogs Rating that you posted on your site and the name of your website. Next, write a description for your blog, add your email address and choose a category where your blog fits in. Last, write a comment and you can finally submit your blog to Blogs Rating.

Click here to submit your blog to Blogs Rating

Posted on December 8, 2010

Gozoof

http://www.gozoof.com/

Gozoof is a free blog directory where you can submit your blog so that people can rate and promote your content across the directory. Gozoof users can also comment and recommend links. Registration is mandatory.

To submit your blog to Gozoof, you need to register first. Then, add the URL and title of your blog and write a description for your site. Last, choose a category and a specific topic to represent your blog.

Click here to submit your blog to Gozoof

Posted on December 4, 2010

InfoListings

http://www.info-listings.com/

InfoListings is a blog directory where you can submit your blog site to obtain more traffic and exposure for your original content. Registration is not mandatory to submit your website to InfoListings. There are two types of submission to choose from: Featured ($29.99 one-time fee) and Regular (free). Please note that for Regular submissions the time to evaluate the inclusion of your blog site inside the directory spans from three to six months.

To submit your website to InfoListings, first you need to choose the type of submission link that you prefer, then add the title, URL of your blog, a description, and then provide your name and e-mail address. Last, select the category your blog corresponds to.

Click here to submit your blog to InfoListings

E-books for btech 2-1 students

2011-03-10T19:03:00.000+05:30

Name : ADS
http://www.ziddu.com/download/6727131/ADS_WW8.chm.html

Name : P&S
http://www.ziddu.com/download/6727218/pt_ww8.pdf.html

Name : DLD
http://www.ziddu.com/download/6727373/DLD_WW8.pdf.html

E-books for btech 1year cse Students

2011-03-10T18:59:00.000+05:30

Name : Let Us C By Yaswanth Kanithkarhttp://www.ziddu.com/download/5458895/Let_Us_C_-_Yashwant_Kanetkar.zip.html
Name : C and Data Structureshttp://www.ziddu.com/download/5474045/c.and.data.structures.ebook.rar.html
Name : M1http://www.ziddu.com/download/5568797/m1.rar.html
Name : MMhttp://www.ziddu.com/download/5568875/MM.rar.html
Name : Data Structure Noteshttp://www.ziddu.com/download/5568563/DATASTRUCTURESNOTES.rar.html

E-books for btech 2-2 cse students

2011-03-10T18:55:00.003+05:30

Name :Environmental science
http://www.ziddu.com/download/4287310/ch.3ed.Elsevier2001Environmentalscience290s.pdf.html
Name: Computer Organisation
http://www.your.vc/showfile-13/computerorganization.pdf
Name : Object Oriented and Analysis
http://www.your.vc/showfile-39/ect_orientedanalysisanddesignwithapplications2ndedpdf.html
Name: Principles_Programming_Languages
http://www.ziddu.com/download/5801063/Principles_Programming_Languages.rar.html
Name: Flathttp://www.ziddu.com/download/5610010/FLAT.rar.html

PROCESS MODEL AND IPC

2011-03-10T16:05:00.002+05:30

Brief about the initial process sequence while the system boots up.

While booting, special process called the 'swapper' or 'scheduler' is created with Process-ID 0. The swapper manages memory allocation for processes and influences CPU allocation. The swapper inturn creates 3 children:

Ø the process dispatcher,

Ø vhand and

Ø dbflush

with IDs 1,2 and 3 respectively.

This is done by executing the file /etc/init. Process dispatcher gives birth to the shell. Unix keeps track of all the processes in an internal data structure called the Process Table (listing command is ps -el).

2. What are various IDs associated with a process?

Unix identifies each process with a unique integer called ProcessID. The process that executes the request for creation of a process is called the 'parent process' whose PID is 'Parent Process ID'. Every process is associated with a particular user called the 'owner' who has privileges over the process. The identification for the user is 'UserID'. Owner is the user who executes the process. Process also has 'Effective User ID' which determines the access privileges for accessing resources like files.

getpid() -process id

getppid() -parent process id

getuid() -user id

geteuid() -effective user id

3. Explain fork() system call.

The `fork()' used to create a new process from an existing process. The new process is called the child process, and the existing process is called the parent. We can tell which is which by checking the return value from `fork()'. The parent gets the child's pid returned to him, but the child gets 0 returned to him.

4. Predict the output of the following program code

main()

{

fork();

printf("Hello World!");

}

Answer:

Hello World!Hello World!

Explanation:

The fork creates a child that is a duplicate of the parent process. The child begins from the fork().All the statements after the call to fork() will be executed twice.(once by the parent process and other by child). The statement before fork() is executed only by the parent process.

5. Predict the output of the following program code

main()

{

fork(); fork(); fork();

printf("Hello World!");

}

Answer:

"Hello World" will be printed 8 times.

Explanation:

2^n times where n is the number of calls to fork()

6. List the system calls used for process management:

System calls Description

fork() To create a new process

exec() To execute a new program in a process

wait() To wait until a created process completes its execution

exit() To exit from a process execution

getpid() To get a process identifier of the current process

getppid() To get parent process identifier

nice() To bias the existing priority of a process

brk() To increase/decrease the data segment size of a process

7. How can you get/set an environment variable from a program?

Getting the value of an environment variable is done by using `getenv()'.

Setting the value of an environment variable is done by using `putenv()'.

8. How can a parent and child process communicate?

A parent and child can communicate through any of the normal inter-process communication schemes (pipes, sockets, message queues, shared memory), but also have some special ways to communicate that take advantage of their relationship as a parent and child. One of the most obvious is that the parent can get the exit status of the child.

9. What is a zombie?

When a program forks and the child finishes before the parent, the kernel still keeps some of its information about the child in case the parent might need it - for example, the parent may need to check the child's exit status. To be able to get this information, the parent calls `wait()'; In the interval between the child terminating and the parent calling `wait()', the child is said to be a `zombie' (If you do `ps', the child will have a `Z' in its status field to indicate this.)

10. What are the process states in Unix?

As a process executes it changes state according to its circumstances. Unix processes have the following states:

Running : The process is either running or it is ready to run .

Waiting : The process is waiting for an event or for a resource.

Stopped : The process has been stopped, usually by receiving a signal.

Zombie : The process is dead but have not been removed from the process table.

11. What Happens when you execute a program?

When you execute a program on your UNIX system, the system creates a special environment for that program. This environment contains everything needed for the system to run the program as if no other program were running on the system. Each process has process context, which is everything that is unique about the state of the program you are currently running. Every time you execute a program the UNIX system does a fork, which performs a series of operations to create a process context and then execute your program in that context. The steps include the following:

Ø Allocate a slot in the process table, a list of currently running programs kept by UNIX.

Ø Assign a unique process identifier (PID) to the process.

Ø iCopy the context of the parent, the process that requested the spawning of the new process.

Ø Return the new PID to the parent process. This enables the parent process to examine or control the process directly.

After the fork is complete, UNIX runs your program.

12. What Happens when you execute a command?

When you enter 'ls' command to look at the contents of your current working directory, UNIX does a series of things to create an environment for ls and the run it: The shell has UNIX perform a fork. This creates a new process that the shell will use to run the ls program. The shell has UNIX perform an exec of the ls program. This replaces the shell program and data with the program and data for ls and then starts running that new program. The ls program is loaded into the new process context, replacing the text and data of the shell. The ls program performs its task, listing the contents of the current directory.

13. What is a Daemon?

A daemon is a process that detaches itself from the terminal and runs, disconnected, in the background, waiting for requests and responding to them. It can also be defined as the background process that does not belong to a terminal session. Many system functions are commonly performed by daemons, including the sendmail daemon, which handles mail, and the NNTP daemon, which handles USENET news. Many other daemons may exist. Some of the most common daemons are:

Ø init: Takes over the basic running of the system when the kernel has finished the boot process.

Ø inetd: Responsible for starting network services that do not have their own stand-alone daemons. For example, inetd usually takes care of incoming rlogin, telnet, and ftp connections.

Ø cron: Responsible for running repetitive tasks on a regular schedule.

14. What is 'ps' command for?

The ps command prints the process status for some or all of the running processes. The information given are the process identification number (PID),the amount of time that the process has taken to execute so far etc.

15. How would you kill a process?

The kill command takes the PID as one argument; this identifies which process to terminate. The PID of a process can be got using 'ps' command.

16. What is an advantage of executing a process in background?

The most common reason to put a process in the background is to allow you to do something else interactively without waiting for the process to complete. At the end of the command you add the special background symbol, &. This symbol tells your shell to execute the given command in the background.

Example: cp *.* ../backup& (cp is for copy)

17. How do you execute one program from within another?

The system calls used for low-level process creation are execlp() and execvp(). The execlp call overlays the existing program with the new one , runs that and exits. The original program gets back control only when an error occurs.

execlp(path,file_name,arguments..); //last argument must be NULL

A variant of execlp called execvp is used when the number of arguments is not known in advance.

execvp(path,argument_array); //argument array should be terminated by NULL

18. What is IPC? What are the various schemes available?

The term IPC (Inter-Process Communication) describes various ways by which different process running on some operating system communicate between each other. Various schemes available are as follows:

Pipes:

One-way communication scheme through which different process can communicate. The problem is that the two processes should have a common ancestor (parent-child relationship). However this problem was fixed with the introduction of named-pipes (FIFO).

Message Queues :

Message queues can be used between related and unrelated processes running on a machine.

Shared Memory:

This is the fastest of all IPC schemes. The memory to be shared is mapped into the address space of the processes (that are sharing). The speed achieved is attributed to the fact that there is no kernel involvement. But this scheme needs synchronization.

Various forms of synchronisation are mutexes, condition-variables, read-write locks, record-locks, and semaphores.

MEMORY MANAGEMENT

2011-03-10T16:04:00.002+05:30

What is the difference between Swapping and Paging?

Swapping:

Whole process is moved from the swap device to the main memory for execution. Process size must be less than or equal to the available main memory. It is easier to implementation and overhead to the system. Swapping systems does not handle the memory more flexibly as compared to the paging systems.

Paging:

Only the required memory pages are moved to main memory from the swap device for execution. Process size does not matter. Gives the concept of the virtual memory.

It provides greater flexibility in mapping the virtual address space into the physical memory of the machine. Allows more number of processes to fit in the main memory simultaneously. Allows the greater process size than the available physical memory. Demand paging systems handle the memory more flexibly.

2. What is major difference between the Historic Unix and the new BSD release of Unix System V in terms of Memory Management?

Historic Unix uses Swapping – entire process is transferred to the main memory from the swap device, whereas the Unix System V uses Demand Paging – only the part of the process is moved to the main memory. Historic Unix uses one Swap Device and Unix System V allow multiple Swap Devices.

3. What is the main goal of the Memory Management?

Ø It decides which process should reside in the main memory,

Ø Manages the parts of the virtual address space of a process which is non-core resident,

Ø Monitors the available main memory and periodically write the processes into the swap device to provide more processes fit in the main memory simultaneously.

4. What is a Map?

A Map is an Array, which contains the addresses of the free space in the swap device that are allocatable resources, and the number of the resource units available there.

This allows First-Fit allocation of contiguous blocks of a resource. Initially the Map contains one entry – address (block offset from the starting of the swap area) and the total number of resources.

Kernel treats each unit of Map as a group of disk blocks. On the allocation and freeing of the resources Kernel updates the Map for accurate information.

5. What scheme does the Kernel in Unix System V follow while choosing a swap device among the multiple swap devices?

Kernel follows Round Robin scheme choosing a swap device among the multiple swap devices in Unix System V.

6. What is a Region?

A Region is a continuous area of a process’s address space (such as text, data and stack). The kernel in a ‘Region Table’ that is local to the process maintains region. Regions are sharable among the process.

7. What are the events done by the Kernel after a process is being swapped out from the main memory?

When Kernel swaps the process out of the primary memory, it performs the following:

Ø Kernel decrements the Reference Count of each region of the process. If the reference count becomes zero, swaps the region out of the main memory,

Ø Kernel allocates the space for the swapping process in the swap device,

Ø Kernel locks the other swapping process while the current swapping operation is going on,

Ø The Kernel saves the swap address of the region in the region table.

8. Is the Process before and after the swap are the same? Give reason.

Process before swapping is residing in the primary memory in its original form. The regions (text, data and stack) may not be occupied fully by the process, there may be few empty slots in any of the regions and while swapping Kernel do not bother about the empty slots while swapping the process out.

After swapping the process resides in the swap (secondary memory) device. The regions swapped out will be present but only the occupied region slots but not the empty slots that were present before assigning.

While swapping the process once again into the main memory, the Kernel referring to the Process Memory Map, it assigns the main memory accordingly taking care of the empty slots in the regions.

9. What do you mean by u-area (user area) or u-block?

This contains the private data that is manipulated only by the Kernel. This is local to the Process, i.e. each process is allocated a u-area.

10. What are the entities that are swapped out of the main memory while swapping the process out of the main memory?

All memory space occupied by the process, process’s u-area, and Kernel stack are swapped out, theoretically.

Practically, if the process’s u-area contains the Address Translation Tables for the process then Kernel implementations do not swap the u-area.

11. What is Fork swap?

fork() is a system call to create a child process. When the parent process calls fork() system call, the child process is created and if there is short of memory then the child process is sent to the read-to-run state in the swap device, and return to the user state without swapping the parent process. When the memory will be available the child process will be swapped into the main memory.

12. What is Expansion swap?

At the time when any process requires more memory than it is currently allocated, the Kernel performs Expansion swap. To do this Kernel reserves enough space in the swap device. Then the address translation mapping is adjusted for the new virtual address space but the physical memory is not allocated. At last Kernel swaps the process into the assigned space in the swap device. Later when the Kernel swaps the process into the main memory this assigns memory according to the new address translation mapping.

13. How the Swapper works?

The swapper is the only process that swaps the processes. The Swapper operates only in the Kernel mode and it does not uses System calls instead it uses internal Kernel functions for swapping. It is the archetype of all kernel process.

14. What are the processes that are not bothered by the swapper? Give Reason.

Ø Zombie process: They do not take any up physical memory.

Ø Processes locked in memories that are updating the region of the process.

Ø Kernel swaps only the sleeping processes rather than the ‘ready-to-run’ processes, as they have the higher probability of being scheduled than the Sleeping processes.

15. What are the requirements for a swapper to work?

The swapper works on the highest scheduling priority. Firstly it will look for any sleeping process, if not found then it will look for the ready-to-run process for swapping. But the major requirement for the swapper to work the ready-to-run process must be core-resident for at least 2 seconds before swapping out. And for swapping in the process must have been resided in the swap device for at least 2 seconds. If the requirement is not satisfied then the swapper will go into the wait state on that event and it is awaken once in a second by the Kernel.

16. What are the criteria for choosing a process for swapping into memory from the swap device?

The resident time of the processes in the swap device, the priority of the processes and the amount of time the processes had been swapped out.

17. What are the criteria for choosing a process for swapping out of the memory to the swap device?

Ø The process’s memory resident time,

Ø Priority of the process and

Ø The nice value.

18. What do you mean by nice value?

Nice value is the value that controls {increments or decrements} the priority of the process. This value that is returned by the nice () system call. The equation for using nice value is:

Priority = (“recent CPU usage”/constant) + (base- priority) + (nice value)

Only the administrator can supply the nice value. The nice () system call works for the running process only. Nice value of one process cannot affect the nice value of the other process.

19. What are conditions on which deadlock can occur while swapping the processes?

Ø All processes in the main memory are asleep.

Ø All ‘ready-to-run’ processes are swapped out.

Ø There is no space in the swap device for the new incoming process that are swapped out of the main memory.

Ø There is no space in the main memory for the new incoming process.

20. What are conditions for a machine to support Demand Paging?

Ø Memory architecture must based on Pages,

Ø The machine must support the ‘restartable’ instructions.

21. What is ‘the principle of locality’?

It’s the nature of the processes that they refer only to the small subset of the total data space of the process. i.e. the process frequently calls the same subroutines or executes the loop instructions.

22. What is the working set of a process?

The set of pages that are referred by the process in the last ‘n’, references, where ‘n’ is called the window of the working set of the process.

23. What is the window of the working set of a process?

The window of the working set of a process is the total number in which the process had referred the set of pages in the working set of the process.

24. What is called a page fault?

Page fault is referred to the situation when the process addresses a page in the working set of the process but the process fails to locate the page in the working set. And on a page fault the kernel updates the working set by reading the page from the secondary device.

25. What are data structures that are used for Demand Paging?

Kernel contains 4 data structures for Demand paging. They are,

Ø Page table entries,

Ø Disk block descriptors,

Ø Page frame data table (pfdata),

Ø Swap-use table.

26. What are the bits that support the demand paging?

Valid, Reference, Modify, Copy on write, Age. These bits are the part of the page table entry, which includes physical address of the page and protection bits.

Page address

Age

Copy on write

Modify

Reference

Valid

Protection

27. How the Kernel handles the fork() system call in traditional Unix and in the System VUnix, while swapping?

Kernel in traditional Unix, makes the duplicate copy of the parent’s address space and attaches it to the child’s process, while swapping. Kernel in System V Unix, manipulates the region tables, page table, and pfdata table entries, by incrementing the reference count of the region table of shared regions.

28. Difference between the fork() and vfork() system call?

During the fork() system call the Kernel makes a copy of the parent process’s address space and attaches it to the child process.

But the vfork() system call do not makes any copy of the parent’s address space, so it is faster than the fork() system call. The child process as a result of the vfork() system call executes exec() system call. The child process from vfork() system call executes in the parent’s address space (this can overwrite the parent’s data and stack ) which suspends the parent process until the child process exits.

29. What is BSS(Block Started by Symbol)?

A data representation at the machine level, that has initial values when a program starts and tells about how much space the kernel allocates for the un-initialized data. Kernel initializes it to zero at run-time.

30. What is Page-Stealer process?

This is the Kernel process that makes rooms for the incoming pages, by swapping the memory pages that are not the part of the working set of a process. Page-Stealer is created by the Kernel at the system initialization and invokes it throughout the lifetime of the system. Kernel locks a region when a process faults on a page in the region, so that page stealer cannot steal the page, which is being faulted in.

31. Name two paging states for a page in memory?

The two paging states are:

Ø The page is aging and is not yet eligible for swapping,

Ø The page is eligible for swapping but not yet eligible for reassignment to other virtual address space.

32. What are the phases of swapping a page from the memory?

Ø Page stealer finds the page eligible for swapping and places the page number in the list of pages to be swapped.

Ø Kernel copies the page to a swap device when necessary and clears the valid bit in the page table entry, decrements the pfdata reference count, and places the pfdata table entry at the end of the free list if its reference count is 0.

33. What is page fault? Its types?

Page fault refers to the situation of not having a page in the main memory when any process references it.

There are two types of page fault :

Ø Validity fault,

Ø Protection fault.

34. In what way the Fault Handlers and the Interrupt handlers are different?

Fault handlers are also an interrupt handler with an exception that the interrupt handlers cannot sleep. Fault handlers sleep in the context of the process that caused the memory fault. The fault refers to the running process and no arbitrary processes are put to sleep.

35. What is validity fault?

If a process referring a page in the main memory whose valid bit is not set, it results in validity fault.

The valid bit is not set for those pages:

Ø that are outside the virtual address space of a process,

Ø that are the part of the virtual address space of the process but no physical address is assigned to it.

36. What does the swapping system do if it identifies the illegal page for swapping?

If the disk block descriptor does not contain any record of the faulted page, then this causes the attempted memory reference is invalid and the kernel sends a “Segmentation violation” signal to the offending process. This happens when the swapping system identifies any invalid memory reference.

37. What are states that the page can be in, after causing a page fault?

Ø On a swap device and not in memory,

Ø On the free page list in the main memory,

Ø In an executable file,

Ø Marked “demand zero”,

Ø Marked “demand fill”.

38. In what way the validity fault handler concludes?

Ø It sets the valid bit of the page by clearing the modify bit.

Ø It recalculates the process priority.

39. At what mode the fault handler executes?

At the Kernel Mode.

40. What do you mean by the protection fault?

Protection fault refers to the process accessing the pages, which do not have the access permission. A process also incur the protection fault when it attempts to write a page whose copy on write bit was set during the fork() system call.

41. How the Kernel handles the copy on write bit of a page, when the bit is set?

In situations like, where the copy on write bit of a page is set and that page is shared by more than one process, the Kernel allocates new page and copies the content to the new page and the other processes retain their references to the old page. After copying the Kernel updates the page table entry with the new page number. Then Kernel decrements the reference count of the old pfdata table entry.

In cases like, where the copy on write bit is set and no processes are sharing the page, the Kernel allows the physical page to be reused by the processes. By doing so, it clears the copy on write bit and disassociates the page from its disk copy (if one exists), because other process may share the disk copy. Then it removes the pfdata table entry from the page-queue as the new copy of the virtual page is not on the swap device. It decrements the swap-use count for the page and if count drops to 0, frees the swap space.

42. For which kind of fault the page is checked first?

The page is first checked for the validity fault, as soon as it is found that the page is invalid (valid bit is clear), the validity fault handler returns immediately, and the process incur the validity page fault. Kernel handles the validity fault and the process will incur the protection fault if any one is present.

43. In what way the protection fault handler concludes?

After finishing the execution of the fault handler, it sets the modify and protection bits and clears the copy on write bit. It recalculates the process-priority and checks for signals.

44. How the Kernel handles both the page stealer and the fault handler?

The page stealer and the fault handler thrash because of the shortage of the memory. If the sum of the working sets of all processes is greater that the physical memory then the fault handler will usually sleep because it cannot allocate pages for a process. This results in the reduction of the system throughput because Kernel spends too much time in overhead, rearranging the memory in the frantic pace.

FILE MANAGEMENT IN UNIX

2011-03-10T16:03:00.002+05:30

How are devices represented in UNIX?

All devices are represented by files called special filesthat are located in/dev directory. Thus, device files and other files are named and accessed in the same way. A 'regular file' is just an ordinary data file in the disk. A 'block special file' represents a device with characteristics similar to a disk (data transfer in terms of blocks). A 'character special file' represents a device with characteristics similar to a keyboard (data transfer is by stream of bits in sequential order).

2. What is 'inode'?

All UNIX files have its description stored in a structure called 'inode'. The inode contains info about the file-size, its location, time of last access, time of last modification, permission and so on. Directories are also represented as files and have an associated inode. In addition to descriptions about the file, the inode contains pointers to the data blocks of the file. If the file is large, inode has indirect pointer to a block of pointers to additional data blocks (this further aggregates for larger files). A block is typically 8k.

Inode consists of the following fields:

Ø File owner identifier

Ø File type

Ø File access permissions

Ø File access times

Ø Number of links

Ø File size

Ø Location of the file data

3. Brief about the directory representation in UNIX

A Unix directory is a file containing a correspondence between filenames and inodes. A directory is a special file that the kernel maintains. Only kernel modifies directories, but processes can read directories. The contents of a directory are a list of filename and inode number pairs. When new directories are created, kernel makes two entries named '.' (refers to the directory itself) and '..' (refers to parent directory).

System call for creating directory is mkdir (pathname, mode).

4. What are the Unix system calls for I/O?

Ø open(pathname,flag,mode) - open file

Ø creat(pathname,mode) - create file

Ø close(filedes) - close an open file

Ø read(filedes,buffer,bytes) - read data from an open file

Ø write(filedes,buffer,bytes) - write data to an open file

Ø lseek(filedes,offset,from) - position an open file

Ø dup(filedes) - duplicate an existing file descriptor

Ø dup2(oldfd,newfd) - duplicate to a desired file descriptor

Ø fcntl(filedes,cmd,arg) - change properties of an open file

Ø ioctl(filedes,request,arg) - change the behaviour of an open file

The difference between fcntl anf ioctl is that the former is intended for any open file, while the latter is for device-specific operations.

5. How do you change File Access Permissions?

Every file has following attributes:

Ø owner's user ID ( 16 bit integer )

Ø owner's group ID ( 16 bit integer )

Ø File access mode word

'r w x -r w x- r w x'

(user permission-group permission-others permission)

r-read, w-write, x-execute

To change the access mode, we use chmod(filename,mode).

Example 1:

To change mode of myfile to 'rw-rw-r--' (ie. read, write permission for user - read,write permission for group - only read permission for others) we give the args as:

chmod(myfile,0664) .

Each operation is represented by discrete values

'r' is 4

'w' is 2

'x' is 1

Therefore, for 'rw' the value is 6(4+2).

Example 2:

To change mode of myfile to 'rwxr--r--' we give the args as:

chmod(myfile,0744).

6. What are links and symbolic links in UNIX file system?

A link is a second name (not a file) for a file. Links can be used to assign more than one name to a file, but cannot be used to assign a directory more than one name or link filenames on different computers.

Symbolic link 'is' a file that only contains the name of another file.Operation on the symbolic link is directed to the file pointed by the it.Both the limitations of links are eliminated in symbolic links.

Commands for linking files are:

Link ln filename1 filename2

Symbolic link ln -s filename1 filename2

7. What is a FIFO?

FIFO are otherwise called as 'named pipes'. FIFO (first-in-first-out) is a special file which is said to be data transient. Once data is read from named pipe, it cannot be read again. Also, data can be read only in the order written. It is used in interprocess communication where a process writes to one end of the pipe (producer) and the other reads from the other end (consumer).

8. How do you create special files like named pipes and device files?

The system call mknod creates special files in the following sequence.

1. kernel assigns new inode,

2. sets the file type to indicate that the file is a pipe, directory or special file,

3. If it is a device file, it makes the other entries like major, minor device numbers.

For example:

If the device is a disk, major device number refers to the disk controller and minor device number is the disk.

9. Discuss the mount and unmount system calls

The privileged mount system call is used to attach a file system to a directory of another file system; the unmount system call detaches a file system. When you mount another file system on to your directory, you are essentially splicing one directory tree onto a branch in another directory tree. The first argument to mount call is the mount point, that is , a directory in the current file naming system. The second argument is the file system to mount to that point. When you insert a cdrom to your unix system's drive, the file system in the cdrom automatically mounts to /dev/cdrom in your system.

10. How does the inode map to data block of a file?

Inode has 13 block addresses. The first 10 are direct block addresses of the first 10 data blocks in the file. The 11th address points to a one-level index block. The 12th address points to a two-level (double in-direction) index block. The 13th address points to a three-level(triple in-direction)index block. This provides a very large maximum file size with efficient access to large files, but also small files are accessed directly in one disk read.

11. What is a shell?

A shell is an interactive user interface to an operating system services that allows an user to enter commands as character strings or through a graphical user interface. The shell converts them to system calls to the OS or forks off a process to execute the command. System call results and other information from the OS are presented to the user through an interactive interface. Commonly used shells are sh,csh,ks etc.

OPERATING SYSTEMS(OS)

2011-03-10T16:02:00.002+05:30

Following are a few basic questions that cover the essentials of OS:

1. Explain the concept of Reentrancy.
It is a useful, memory-saving technique for multiprogrammed timesharing systems. A Reentrant Procedure is one in which multiple users can share a single copy of a program during the same period. Reentrancy has 2 key aspects: The program code cannot modify itself, and the local data for each user process must be stored separately. Thus, the permanent part is the code, and the temporary part is the pointer back to the calling program and local variables used by that program. Each execution instance is called activation. It executes the code in the permanent part, but has its own copy of local variables/parameters. The temporary part associated with each activation is the activation record. Generally, the activation record is kept on the stack.
Note: A reentrant procedure can be interrupted and called by an interrupting program, and still execute correctly on returning to the procedure.

2. Explain Belady's Anomaly.
Also called FIFO anomaly. Usually, on increasing the number of frames allocated to a process' virtual memory, the process execution is faster, because fewer page faults occur. Sometimes, the reverse happens, i.e., the execution time increases even when more frames are allocated to the process. This is Belady's Anomaly. This is true for certain page reference patterns.

3. What is a binary semaphore? What is its use?
A binary semaphore is one, which takes only 0 and 1 as values. They are used to implement mutual exclusion and synchronize concurrent processes.

4. What is thrashing?
It is a phenomenon in virtual memory schemes when the processor spends most of its time swapping pages, rather than executing instructions. This is due to an inordinate number of page faults.

5. List the Coffman's conditions that lead to a deadlock.
Ø Mutual Exclusion: Only one process may use a critical resource at a time.
Ø Hold & Wait: A process may be allocated some resources while waiting for others.
Ø No Pre-emption: No resource can be forcible removed from a process holding it.
Ø Circular Wait: A closed chain of processes exist such that each process holds at least one resource needed by another process in the chain.

6. What are short-, long- and medium-term scheduling?
Long term scheduler determines which programs are admitted to the system for processing. It controls the degree of multiprogramming. Once admitted, a job becomes a process.
Medium term scheduling is part of the swapping function. This relates to processes that are in a blocked or suspended state. They are swapped out of real-memory until they are ready to execute. The swapping-in decision is based on memory-management criteria.
Short term scheduler, also know as a dispatcher executes most frequently, and makes the finest-grained decision of which process should execute next. This scheduler is invoked whenever an event occurs. It may lead to interruption of one process by preemption.

7. What are turnaround time and response time?
Turnaround time is the interval between the submission of a job and its completion. Response time is the interval between submission of a request, and the first response to that request.

8. What are the typical elements of a process image?
Ø User data: Modifiable part of user space. May include program data, user stack area, and programs that may be modified.
Ø User program: The instructions to be executed.
Ø System Stack: Each process has one or more LIFO stacks associated with it. Used to store parameters and calling addresses for procedure and system calls.
Ø Process control Block (PCB): Info needed by the OS to control processes.

9. What is the Translation Lookaside Buffer (TLB)?
In a cached system, the base addresses of the last few referenced pages is maintained in registers called the TLB that aids in faster lookup. TLB contains those page-table entries that have been most recently used. Normally, each virtual memory reference causes 2 physical memory accesses-- one to fetch appropriate page-table entry, and one to fetch the desired data. Using TLB in-between, this is reduced to just one physical memory access in cases of TLB-hit.

10. What is the resident set and working set of a process?
Resident set is that portion of the process image that is actually in real-memory at a particular instant. Working set is that subset of resident set that is actually needed for execution. (Relate this to the variable-window size method for swapping techniques.)

11. When is a system in safe state?
The set of dispatchable processes is in a safe state if there exists at least one temporal order in which all processes can be run to completion without resulting in a deadlock.

12. What is cycle stealing?
We encounter cycle stealing in the context of Direct Memory Access (DMA). Either the DMA controller can use the data bus when the CPU does not need it, or it may force the CPU to temporarily suspend operation. The latter technique is called cycle stealing. Note that cycle stealing can be done only at specific break points in an instruction cycle.

13. What is meant by arm-stickiness?
If one or a few processes have a high access rate to data on one track of a storage disk, then they may monopolize the device by repeated requests to that track. This generally happens with most common device scheduling algorithms (LIFO, SSTF, C-SCAN, etc). High-density multisurface disks are more likely to be affected by this than low density ones.

14. What are the stipulations of C2 level security?
C2 level security provides for:
Ø Discretionary Access Control
Ø Identification and Authentication
Ø Auditing
Ø Resource reuse

15. What is busy waiting?
The repeated execution of a loop of code while waiting for an event to occur is called busy-waiting. The CPU is not engaged in any real productive activity during this period, and the process does not progress toward completion.

16. Explain the popular multiprocessor thread-scheduling strategies.
Ø Load Sharing: Processes are not assigned to a particular processor. A global queue of threads is maintained. Each processor, when idle, selects a thread from this queue. Note that load balancing refers to a scheme where work is allocated to processors on a more permanent basis.
Ø Gang Scheduling: A set of related threads is scheduled to run on a set of processors at the same time, on a 1-to-1 basis. Closely related threads / processes may be scheduled this way to reduce synchronization blocking, and minimize process switching. Group scheduling predated this strategy.
Ø Dedicated processor assignment: Provides implicit scheduling defined by assignment of threads to processors. For the duration of program execution, each program is allocated a set of processors equal in number to the number of threads in the program. Processors are chosen from the available pool.
Ø Dynamic scheduling: The number of thread in a program can be altered during the course of execution.

17. When does the condition 'rendezvous' arise?
In message passing, it is the condition in which, both, the sender and receiver are blocked until the message is delivered.

18. What is a trap and trapdoor?
Trapdoor is a secret undocumented entry point into a program used to grant access without normal methods of access authentication. A trap is a software interrupt, usually the result of an error condition.

19. What are local and global page replacements?
Local replacement means that an incoming page is brought in only to the relevant process' address space. Global replacement policy allows any page frame from any process to be replaced. The latter is applicable to variable partitions model only.

20. Define latency, transfer and seek time with respect to disk I/O.
Seek time is the time required to move the disk arm to the required track. Rotational delay or latency is the time it takes for the beginning of the required sector to reach the head. Sum of seek time (if any) and latency is the access time. Time taken to actually transfer a span of data is transfer time.

21. Describe the Buddy system of memory allocation.
Free memory is maintained in linked lists, each of equal sized blocks. Any such block is of size 2^k. When some memory is required by a process, the block size of next higher order is chosen, and broken into two. Note that the two such pieces differ in address only in their kth bit. Such pieces are called buddies. When any used block is freed, the OS checks to see if its buddy is also free. If so, it is rejoined, and put into the original free-block linked-list.

22. What is time-stamping?
It is a technique proposed by Lamport, used to order events in a distributed system without the use of clocks. This scheme is intended to order events consisting of the transmission of messages. Each system 'i' in the network maintains a counter Ci. Every time a system transmits a message, it increments its counter by 1 and attaches the time-stamp Ti to the message. When a message is received, the receiving system 'j' sets its counter Cj to 1 more than the maximum of its current value and the incoming time-stamp Ti. At each site, the ordering of messages is determined by the following rules: For messages x from site i and y from site j, x precedes y if one of the following conditions holds....(a) if Ti
23. How are the wait/signal operations for monitor different from those for semaphores?
If a process in a monitor signal and no task is waiting on the condition variable, the signal is lost. So this allows easier program design. Whereas in semaphores, every operation affects the value of the semaphore, so the wait and signal operations should be perfectly balanced in the program.

24. In the context of memory management, what are placement and replacement algorithms?
Placement algorithms determine where in available real-memory to load a program. Common methods are first-fit, next-fit, best-fit. Replacement algorithms are used when memory is full, and one process (or part of a process) needs to be swapped out to accommodate a new program. The replacement algorithm determines which are the partitions to be swapped out.

25. In loading programs into memory, what is the difference between load-time dynamic linking and run-time dynamic linking?
For load-time dynamic linking: Load module to be loaded is read into memory. Any reference to a target external module causes that module to be loaded and the references are updated to a relative address from the start base address of the application module.
With run-time dynamic loading: Some of the linking is postponed until actual reference during execution. Then the correct module is loaded and linked.

26. What are demand- and pre-paging?
With demand paging, a page is brought into memory only when a location on that page is actually referenced during execution. With pre-paging, pages other than the one demanded by a page fault are brought in. The selection of such pages is done based on common access patterns, especially for secondary memory devices.

27. Paging a memory management function, while multiprogramming a processor management function, are the two interdependent?
Yes.

28. What is page cannibalizing?
Page swapping or page replacements are called page cannibalizing.

29. What has triggered the need for multitasking in PCs?
Ø Increased speed and memory capacity of microprocessors together with the support fir virtual memory and
Ø Growth of client server computing

30. What are the four layers that Windows NT have in order to achieve independence?
Ø Hardware abstraction layer
Ø Kernel
Ø Subsystems
Ø System Services.

31. What is SMP?
To achieve maximum efficiency and reliability a mode of operation known as symmetric multiprocessing is used. In essence, with SMP any process or threads can be assigned to any processor.

32. What are the key object oriented concepts used by Windows NT?
Ø Encapsulation
Ø Object class and instance

33. Is Windows NT a full blown object oriented operating system? Give reasons.
No Windows NT is not so, because its not implemented in object oriented language and the data structures reside within one executive component and are not represented as objects and it does not support object oriented capabilities .

34. What is a drawback of MVT?
It does not have the features like
Ø ability to support multiple processors
Ø virtual storage
Ø source level debugging

35. What is process spawning?
When the OS at the explicit request of another process creates a process, this action is called process spawning.

36. How many jobs can be run concurrently on MVT?
15 jobs

37. List out some reasons for process termination.
Ø Normal completion
Ø Time limit exceeded
Ø Memory unavailable
Ø Bounds violation
Ø Protection error
Ø Arithmetic error
Ø Time overrun
Ø I/O failure
Ø Invalid instruction
Ø Privileged instruction
Ø Data misuse
Ø Operator or OS intervention
Ø Parent termination.

38. What are the reasons for process suspension?
Ø swapping
Ø interactive user request
Ø timing
Ø parent process request

39. What is process migration?
It is the transfer of sufficient amount of the state of process from one machine to the target machine

40. What is mutant?
In Windows NT a mutant provides kernel mode or user mode mutual exclusion with the notion of ownership.

41. What is an idle thread?
The special thread a dispatcher will execute when no ready thread is found.

42. What is FtDisk?
It is a fault tolerance disk driver for Windows NT.

43. What are the possible threads a thread can have?
Ø Ready
Ø Standby
Ø Running
Ø Waiting
Ø Transition
Ø Terminated.

44. What are rings in Windows NT?
Windows NT uses protection mechanism called rings provides by the process to implement separation between the user mode and kernel mode.

45. What is Executive in Windows NT?
In Windows NT, executive refers to the operating system code that runs in kernel mode.

46. What are the sub-components of I/O manager in Windows NT?
Ø Network redirector/ Server
Ø Cache manager.
Ø File systems
Ø Network driver
Ø Device driver

47. What are DDks? Name an operating system that includes this feature.
DDks are device driver kits, which are equivalent to SDKs for writing device drivers. Windows NT includes DDks.

48. What level of security does Windows NT meets?
C2 level security.

COMPUTER NETWORKS(CN)

2011-03-10T16:01:00.002+05:30

What are the two types of transmission technology available?
(i) Broadcast and (ii) point-to-point

2. What is subnet?
A generic term for section of a large networks usually separated by a bridge or router.

3. Difference between the communication and transmission.
Transmission is a physical movement of information and concern issues like bit polarity, synchronisation, clock etc.
Communication means the meaning full exchange of information between two communication media.

4. What are the possible ways of data exchange?
(i) Simplex (ii) Half-duplex (iii) Full-duplex.

5. What is SAP?
Series of interface points that allow other computers to communicate with the other layers of network protocol stack.

6. What do you meant by "triple X" in Networks?
The function of PAD (Packet Assembler Disassembler) is described in a document known as X.3. The standard protocol has been defined between the terminal and the PAD, called X.28; another standard protocol exists between hte PAD and the network, called X.29. Together, these three recommendations are often called "triple X"

7. What is frame relay, in which layer it comes?
Frame relay is a packet switching technology. It will operate in the data link layer.

8. What is terminal emulation, in which layer it comes?
Telnet is also called as terminal emulation. It belongs to application layer.

9. What is Beaconing?
The process that allows a network to self-repair networks problems. The stations on the network notify the other stations on the ring when they are not receiving the transmissions. Beaconing is used in Token ring and FDDI networks.

10. What is redirector?
Redirector is software that intercepts file or prints I/O requests and translates them into network requests. This comes under presentation layer.

11. What is NETBIOS and NETBEUI?
NETBIOS is a programming interface that allows I/O requests to be sent to and received from a remote computer and it hides the networking hardware from applications.
NETBEUI is NetBIOS extended user interface. A transport protocol designed by microsoft and IBM for the use on small subnets.

12. What is RAID?
A method for providing fault tolerance by using multiple hard disk drives.

13. What is passive topology?
When the computers on the network simply listen and receive the signal, they are referred to as passive because they don’t amplify the signal in any way. Example for passive topology - linear bus.

14. What is Brouter?
Hybrid devices that combine the features of both bridges and routers.

15. What is cladding?
A layer of a glass surrounding the center fiber of glass inside a fiber-optic cable.

16. What is point-to-point protocol
A communications protocol used to connect computers to remote networking services including Internet service providers.

17. How Gateway is different from Routers?
A gateway operates at the upper levels of the OSI model and translates information between two completely different network architectures or data formats

18. What is attenuation?
The degeneration of a signal over distance on a network cable is called attenuation.

19. What is MAC address?
The address for a device as it is identified at the Media Access Control (MAC) layer in the network architecture. MAC address is usually stored in ROM on the network adapter card and is unique.

20. Difference between bit rate and baud rate.
Bit rate is the number of bits transmitted during one second whereas baud rate refers to the number of signal units per second that are required to represent those bits.
baud rate = bit rate / N
where N is no-of-bits represented by each signal shift.

21. What is Bandwidth?
Every line has an upper limit and a lower limit on the frequency of signals it can carry. This limited range is called the bandwidth.

22. What are the types of Transmission media?
Signals are usually transmitted over some transmission media that are broadly classified in to two categories.
a) Guided Media:
These are those that provide a conduit from one device to another that include twisted-pair, coaxial cable and fiber-optic cable. A signal traveling along any of these media is directed and is contained by the physical limits of the medium. Twisted-pair and coaxial cable use metallic that accept and transport signals in the form of electrical current. Optical fiber is a glass or plastic cable that accepts and transports signals in the form of light.
b) Unguided Media:
This is the wireless media that transport electromagnetic waves without using a physical conductor. Signals are broadcast either through air. This is done through radio communication, satellite communication and cellular telephony.

23. What is Project 802?
It is a project started by IEEE to set standards to enable intercommunication between equipment from a variety of manufacturers. It is a way for specifying functions of the physical layer, the data link layer and to some extent the network layer to allow for interconnectivity of major LAN
protocols.
It consists of the following:
Ø 802.1 is an internetworking standard for compatibility of different LANs and MANs across protocols.
Ø 802.2 Logical link control (LLC) is the upper sublayer of the data link layer which is non-architecture-specific, that is remains the same for all IEEE-defined LANs.
Ø Media access control (MAC) is the lower sublayer of the data link layer that contains some distinct modules each carrying proprietary information specific to the LAN product being used. The modules are Ethernet LAN (802.3), Token ring LAN (802.4), Token bus LAN (802.5).
Ø 802.6 is distributed queue dual bus (DQDB) designed to be used in MANs.

24. What is Protocol Data Unit?
The data unit in the LLC level is called the protocol data unit (PDU). The PDU contains of four fields a destination service access point (DSAP), a source service access point (SSAP), a control field and an information field. DSAP, SSAP are addresses used by the LLC to identify the protocol stacks on the receiving and sending machines that are generating and using the data. The control field specifies whether the PDU frame is a information frame (I - frame) or a supervisory frame (S - frame) or a unnumbered frame (U - frame).

25. What are the different type of networking / internetworking devices?
Repeater:
Also called a regenerator, it is an electronic device that operates only at physical layer. It receives the signal in the network before it becomes weak, regenerates the original bit pattern and puts the refreshed copy back in to the link.
Bridges:
These operate both in the physical and data link layers of LANs of same type. They divide a larger network in to smaller segments. They contain logic that allow them to keep the traffic for each segment separate and thus are repeaters that relay a frame only the side of the segment containing the intended recipent and control congestion.
Routers:
They relay packets among multiple interconnected networks (i.e. LANs of different type). They operate in the physical, data link and network layers. They contain software that enable them to determine which of the several possible paths is the best for a particular transmission.
Gateways:
They relay packets among networks that have different protocols (e.g. between a LAN and a WAN). They accept a packet formatted for one protocol and convert it to a packet formatted for another protocol before forwarding it. They operate in all seven layers of the OSI model.

26. What is ICMP?
ICMP is Internet Control Message Protocol, a network layer protocol of the TCP/IP suite used by hosts and gateways to send notification of datagram problems back to the sender. It uses the echo test / reply to test whether a destination is reachable and responding. It also handles both control and error messages.

27. What are the data units at different layers of the TCP / IP protocol suite?
The data unit created at the application layer is called a message, at the transport layer the data unit created is called either a segment or an user datagram, at the network layer the data unit created is called the datagram, at the data link layer the datagram is encapsulated in to a frame and finally transmitted as signals along the transmission media.

28. What is difference between ARP and RARP?
The address resolution protocol (ARP) is used to associate the 32 bit IP address with the 48 bit physical address, used by a host or a router to find the physical address of another host on its network by sending a ARP query packet that includes the IP address of the receiver.
The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.

29. What is the minimum and maximum length of the header in the TCP segment and IP datagram?
The header should have a minimum length of 20 bytes and can have a maximum length of 60 bytes.

30. What is the range of addresses in the classes of internet addresses?
Class A 0.0.0.0 - 127.255.255.255
Class B 128.0.0.0 - 191.255.255.255
Class C 192.0.0.0 - 223.255.255.255
Class D 224.0.0.0 - 239.255.255.255
Class E 240.0.0.0 - 247.255.255.255

31. What is the difference between TFTP and FTP application layer protocols?
The Trivial File Transfer Protocol (TFTP) allows a local host to obtain files from a remote host but does not provide reliability or security. It uses the fundamental packet delivery services offered by UDP.
The File Transfer Protocol (FTP) is the standard mechanism provided by TCP / IP for copying a file from one host to another. It uses the services offer by TCP and so is reliable and secure. It establishes two connections (virtual circuits) between the hosts, one for data transfer and another for control information.

32. What are major types of networks and explain?
Ø Server-based network
Ø Peer-to-peer network
Peer-to-peer network, computers can act as both servers sharing resources and as clients using the resources.
Server-based networks provide centralized control of network resources and rely on server computers to provide security and network administration

33. What are the important topologies for networks?
Ø BUS topology:
In this each computer is directly connected to primary network cable in a single line.
Advantages:
Inexpensive, easy to install, simple to understand, easy to extend.

Ø STAR topology:
In this all computers are connected using a central hub.
Advantages:
Can be inexpensive, easy to install and reconfigure and easy to trouble shoot physical problems.

Ø RING topology:
In this all computers are connected in loop.
Advantages:
All computers have equal access to network media, installation can be simple, and signal does not degrade as much as in other topologies because each computer regenerates it.

34. What is mesh network?
A network in which there are multiple network links between computers to provide multiple paths for data to travel.

35. What is difference between baseband and broadband transmission?
In a baseband transmission, the entire bandwidth of the cable is consumed by a single signal. In broadband transmission, signals are sent on multiple frequencies, allowing multiple signals to be sent simultaneously.

36. Explain 5-4-3 rule?
In a Ethernet network, between any two points on the network ,there can be no more than five network segments or four repeaters, and of those five segments only three of segments can be populated.

37. What MAU?
In token Ring , hub is called Multistation Access Unit(MAU).

38. What is the difference between routable and non- routable protocols?
Routable protocols can work with a router and can be used to build large networks. Non-Routable protocols are designed to work on small, local networks and cannot be used with a router

39. Why should you care about the OSI Reference Model?
It provides a framework for discussing network operations and design.

40. What is logical link control?
One of two sublayers of the data link layer of OSI reference model, as defined by the IEEE 802 standard. This sublayer is responsible for maintaining the link between computers when they are sending data across the physical network connection.

41. What is virtual channel?
Virtual channel is normally a connection from one source to one destination, although multicast connections are also permitted. The other name for virtual channel is virtual circuit.

42. What is virtual path?
Along any transmission path from a given source to a given destination, a group of virtual circuits can be grouped together into what is called path.

43. What is packet filter?
Packet filter is a standard router equipped with some extra functionality. The extra functionality allows every incoming or outgoing packet to be inspected. Packets meeting some criterion are forwarded normally. Those that fail the test are dropped.

44. What is traffic shaping?
One of the main causes of congestion is that traffic is often busy. If hosts could be made to transmit at a uniform rate, congestion would be less common. Another open loop method to help manage congestion is forcing the packet to be transmitted at a more predictable rate. This is called traffic shaping.

45. What is multicast routing?
Sending a message to a group is called multicasting, and its routing algorithm is called multicast routing.

46. What is region?
When hierarchical routing is used, the routers are divided into what we will call regions, with each router knowing all the details about how to route packets to destinations within its own region, but knowing nothing about the internal structure of other regions.

47. What is silly window syndrome?
It is a problem that can ruin TCP performance. This problem occurs when data are passed to the sending TCP entity in large blocks, but an interactive application on the receiving side reads 1 byte at a time.

48. What are Digrams and Trigrams?
The most common two letter combinations are called as digrams. e.g. th, in, er, re and an. The most common three letter combinations are called as trigrams. e.g. the, ing, and, and ion.

49. Expand IDEA.
IDEA stands for International Data Encryption Algorithm.

50. What is wide-mouth frog?
Wide-mouth frog is the simplest known key distribution center (KDC) authentication protocol.

51. What is Mail Gateway?
It is a system that performs a protocol translation between different electronic mail delivery protocols.

52. What is IGP (Interior Gateway Protocol)?
It is any routing protocol used within an autonomous system.

53. What is EGP (Exterior Gateway Protocol)?
It is the protocol the routers in neighboring autonomous systems use to identify the set of networks that can be reached within or via each autonomous system.

54. What is autonomous system?
It is a collection of routers under the control of a single administrative authority and that uses a common Interior Gateway Protocol.

55. What is BGP (Border Gateway Protocol)?
It is a protocol used to advertise the set of networks that can be reached with in an autonomous system. BGP enables this information to be shared with the autonomous system. This is newer than EGP (Exterior Gateway Protocol).

56. What is Gateway-to-Gateway protocol?
It is a protocol formerly used to exchange routing information between Internet core routers.

57. What is NVT (Network Virtual Terminal)?
It is a set of rules defining a very simple virtual terminal interaction. The NVT is used in the start of a Telnet session.

58. What is a Multi-homed Host?
It is a host that has a multiple network interfaces and that requires multiple IP addresses is called as a Multi-homed Host.

59. What is Kerberos?
It is an authentication service developed at the Massachusetts Institute of Technology. Kerberos uses encryption to prevent intruders from discovering passwords and gaining unauthorized access to files.

60. What is OSPF?
It is an Internet routing protocol that scales well, can route traffic along multiple paths, and uses knowledge of an Internet's topology to make accurate routing decisions.

61. What is Proxy ARP?
It is using a router to answer ARP requests. This will be done when the originating host believes that a destination is local, when in fact is lies beyond router.

62. What is SLIP (Serial Line Interface Protocol)?
It is a very simple protocol used for transmission of IP datagrams across a serial line.

63. What is RIP (Routing Information Protocol)?
It is a simple protocol used to exchange information between the routers.

64. What is source route?
It is a sequence of IP addresses identifying the route a datagram must follow. A source route may optionally be included in an IP datagram header.

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