All About Computers

CCNA 1 Chapter 4 V4.0 Answers

2010-02-06T14:36:00.000+08:00

CCNA Discovery 4.1 - CCNA Discovery Answers
http://ccna-discovery-4.blogspot.com/
CCNA 1 Chapter 4 V4.0
Labels: CCNA 1 Chapter 4 V4.0
1) Which definition describes the term Internet?
a group of PCs connected together on a LAN
a group of PCs connected together by an ISP
* a network of networks that connects countries around the world
a worldwide collection of networks controlled by a single organization
2) What type of connection point is a point of presence (POP)?
between a client and a host
between two local networks
between a computer and a switch
* between an ISP and a home-based LAN
3) What is the term for the group of high-speed data links that interconnect ISPs?
Internet LAN
ISP backbone
Internet gateways
Internet providers
* Internet backbone
4) Which device can act as a router, switch, and wireless access point in one package?
hub
bridge
modem
repeater
* ISR
5) What are three characteristics of business class ISP service? (Choose three.)
* fast connections
* extra web space
free Windows upgrade
cheapest cost available to all users
* additional e-mail accounts
replacement hardware at no cost
6) What is a major characteristic of asymmetric Internet service?
Download speeds and upload speeds are equal.
Download speeds are slower than upload speeds.
* Upload speeds and download speeds are different.
Upload speeds and download speeds are irrelevant.
7) Which three elements are required to successfully connect to the Internet? (Choose
three.)
* an IP address
file sharing enabled
* a network connection
CCNA Discovery 4.1 - CCNA Discovery Answers
http://ccna-discovery-4.blogspot.com/
server services enabled
* access to an Internet service provider
an address obtained directly from the RIR
8) What term describes each router through which a packet travels when moving
between source and destination networks?
NOC
ISP
* hop
segment
9) What does the tracert command test?
NIC functionality
the ISP bandwidth
* the network path to a destination
the destination application functionality
10) What type of end-user connectivity requires that an ISP have a DSLAM device in
their network?
analog technology
cable modem technology
* digital subscriber line technology
wireless technology
11) Why would an ISP require a CMTS device on their network?
* to connect end users using cable technology
to connect end users using analog technology
to connect end users using wireless technology
to connect end users using digital subscriber line technology

12

Refer to the graphic. What type of cabling is shown?
CCNA Discovery 4.1 - CCNA Discovery Answers
http://ccna-discovery-4.blogspot.com/
STP
UTP
coax
*Fiber

13.Refer to the graphic. What type of cabling is shown?
STP
* UTP
coax
fiber
14) Which two places are most appropriate to use UTP cabling? (Choose two.)
between buildings
* in a home office network
where EMI is an issue
in a cable TV network
* inside a school building
in a manufacturing environment with hundreds of electrical devices
15) What does adherence to cabling standards ensure?
data security
no loss of signal
no electromagnetic interference
* reliable data communications

16. Refer to the graphic. What type of cable is shown?
* crossover
eight coax channels
multimode fiber
single-mode fiber
straight-through
17) What connector is used to terminate Ethernet unshielded twisted pair (UTP)
cabling?
ST
BNC
RJ-11
* RJ-45
18) Which two characteristics describe copper patch panels? (Choose two.)
uses RJ-11 jacks
* uses RJ-45 jacks
supports only data transmissions
* allows quick rearrangements of network connections
forwards transmissions based on MAC addresses
19) What are two advantages of cable management? (Choose two.)
requires no preplanning
* aids in isolation of cabling problems
* protects cables from physical damage
provides compliance with future standards
provides a short-term solution for cable installation
20) What are two common causes of signal degradation when using UTP cabling?
(Choose two.)
installing cables in conduit
CCNA Discovery 4.1 - CCNA Discovery Answers
http://ccna-discovery-4.blogspot.com/
* having improper termination
losing light over long distances
installing low quality cable shielding
* using low quality cables or connectors
21) What are three commonly followed standards for constructing and installing
cabling? (Choose three.)
* pinouts
* cable lengths
connector color
* connector types
cost per meter (foot)
tensile strength of plastic insulator

How to Configure Windows Server 2003 DNS Service

2010-02-04T16:37:00.002+08:00

To configure the Windows Server 2003 DNS service by using the Configure DNS Server Wizard, follow these steps:

Click Start, point to Administrative Tools, and then click DNS to open the DNS MMC snap-in.
In the navigation pane, click the DNS Server object for your server, right-click the server object, and then click Configure a DNS server to start the Configure DNS server Wizard.
Click Next, click one of the following options, and then click Next:
- Create a forward lookup zone (recommended for small networks)
  This server is authoritative for the DNS names for local resources but forwards all other queries to an ISP or other DNS servers. The Wizard will configure the root hints but not create a reverse lookup zone.
- Create forward and reverse lookup zones (recommended for large networks)
  This server can be authoritative for forward and reverse lookup zones. It can be configured to perform recursive resolution, forward queries to other DNS servers, or both. The wizard configures the root hints.
- Configure root hints only (recommended for advanced users only)
  The wizard configures the root hints only. You can configure forward and reverse lookup zones and forwarders later.
If you clicked Create a forward lookup zone or Create forward and reverse lookup zone in step 3, use one of the following procedures to complete the steps.

Create a Forward Lookup Zone

If you create a forward lookup zone, you can either use your server to maintain the zone, or use the Internet service provider’s (ISP) DNS to maintain the zone, in which case the local server maintains a copy of the zone downloaded from the ISP. The following procedure creates a forward lookup zone which is maintained by your server:

Click This server maintains the zone, and then click Next.
In the Zone name box, type the name of the zone. Make sure that the name is the same as the fully qualified domain name (FQDN) DNS domain name for which the zone is authoritative. Click Next.
Click one of the following three options:
1. Click Allow only secure dynamic updates if the zone is integrated into Active Directory.
2. Click Allow any dynamic updates for all other zones (that is, zones that are not necessarily integrated into Active Directory).
3. Click Do not allow dynamic updates if all updates to this zone are to be made manually. Click Next.
Click Yes, it should forward queries to DNS servers with the following IP address to forward queries for names external to your network to another DNS server located elsewhere on the Internet. Typically, you use this option if you use your ISP’s DNS server for external name resolution queries. Type the forwarding DNS server’s IP address.If you do not want to resolve names outside your network by forwarding queries to an external server, click No, it should not forward queries. Click Next, and then click Finish.

Create Forward and Reverse Lookup Zones

To configure forward and reverse lookup zones, follow these steps:

Click Create forward and reverse lookup zones (recommended for large networks), and then click Next.
Click Yes, create a forward lookup zone now (recommended), and then click Next.
Click Primary zone, click to select the Store the zone in Active Directory (available only if DNS server is a domain controller) check box, and then click Next.
Click the appropriate replication scope option, and then click Next.
In the Zone name box, type the name of the zone. Make sure that the name is the same as the fully qualified domain name (FQDN) DNS domain name for which the zone is authoritative. Click Next.
Click one of the following three options:
1. Click Allow only secure dynamic updates if the zone is integrated into Active Directory.
2. Click Allow any dynamic updates for all other zones (that is, zones that may not be integrated into Active Directory).
3. Click Do not allow dynamic updates if all updates to this zone are to be made manually.
4. Click Next.
Click Yes, create a reverse lookup zone now, and then click Next.
Click Primary zone, click to select the Store the zone in Active Directory (available only if DNS server is a domain controller) check box, and then click Next.
Click the appropriate zone replication method, and then click Next.
Click Network ID, and then type the Network ID portion of your IP address that is exposed to the internet. For example, if your IP address is 10.10.10.10, and the subnet mask is 255.255.255.0, the network address portion of the IP address is 10.10.10. Click Next
Click the appropriate zone dynamic update method, and then click Next.
Click Yes, it should forward queries to DNS servers with the following IP address to forward queries for names external to your network to another DNS server located elsewhere on the Internet. Typically you would use this option if you use your ISP’s DNS server for external name resolution queries. Type the forwarding DNS server’s IP address in the space below.If you prefer not to resolve names outside your network by forwarding queries to an external server, click No, it should not forward queries. Click Next, and then click Finish.

How to Secure the ISA Server Computer with Security Configuration Wizard

2010-02-04T16:35:00.000+08:00

The Microsoft Windows Server 2003 operating system with Service Pack 1 (SP1) includes an attack surface reduction tool called the Security Configuration Wizard (SCW). Depending on the server role you select, the SCW determines the minimum functionality required, and disables functionality that is not required.
When you install Windows Server 2003 SP1 on the ISA Server computer, you can install the SCW and use the wizard to harden the computer.
The SCW guides you through the process of creating, editing, applying, or rolling back a security policy based on the selected roles of the server. The security policies that are created with the SCW are .xml files that, when applied, configure services, network security, specific registry values, audit policy, and if applicable, Internet Information Services (IIS). The SCW includes a role for ISA Server computers.
To apply the appropriate ISA Server roles, perform the following steps

On the ISA Server computer, click Start, point to Administrative Tools, and then click Security Configuration Wizard.
In the Security Configuration Wizard, on the Welcome page, click Next.
On the Configuration Action page, select Create a new security policy.
On the Select Server page, in Server, type the name or IP address of the ISA Server computer.
On the Processing Security Configuration Database page, click Next.
On the Welcome page of the Role-based Service Configuration page, click Next.
On the Select Server Roles page, select the following, and then click Next:
1. Select Microsoft Internet Security and Acceleration Server 2004, if you are hardening a computer running the ISA Server services (for ISA Server Enterprise Edition, an array member).
2. Select Remote Access/VPN Server, if you will be using the ISA Server computer for virtual private network (VPN) functionality.
  
  On the Select Client Features page, select the default client roles, as appropriate. No special client roles are specifically required for hardening ISA Server. Then, click Next.
On the Select Administration and Other Options page, select the following options:
1. Select Microsoft Internet Security and Acceleration Server 2004 Enterprise Edition: Configuration Storage, if the Configuration Storage server is installed on this computer (for ISA Server Enterprise Edition only).
2. Select Microsoft Internet Security and Acceleration Server 2004 Enterprise Edition: Client installation share, if the Firewall Client share is installed on this computer.
3. Select Microsoft Internet Security and Acceleration Server 2004 Enterprise Edition: MSDE Logging, if ISA Server advanced logging options are installed on this computer.
4. Select Remote Access Quarantine Agent, if you will enable quarantine for ISA Server. (You must have selected the Remote Access/VPN Server server role in step 7.)
On the Select Additional Services page, select the appropriate services and click Next.
Click Next until you finish the wizard.

Source : http://technet.microsoft.com/hi-in/library/cc302501(en-us).aspx

How to configure a remote access policy in Windows Server 2003

2010-02-04T16:26:00.002+08:00

How to configure a remote access policy

By default, two remote access policies are available in Windows Server 2003:

Connections to Microsoft Routing and Remote Access server
This policy matches every remote access connection that is made to the Routing and Remote Access service.
Connections to other access servers
This policy matches every incoming connection, regardless of the network access server type.

Windows Server 2003 uses the Connections to other access servers policy only when one of the following conditions is true:

The Connections to Microsoft Routing and Remote Access server policy is unavailable.
The order of the policies has been changed.

To configure a new remote access security policy, follow these steps:

Click Start, point to Programs, point to Administrative Tools, and then click Routing and Remote Access.
Expand Server_Name, and then click Remote Access Policies. Note If you have not configured remote access, click Configure and Enable Routing and Remote Access on the Action menu, and then follow the steps in the Routing and Remote Access Server Setup Wizard.
Create a new remote access policy. The following example steps illustrate how to create a new remote access policy that explicitly grants remote access permissions to a specific user on certain days. This policy implicitly blocks access on other days.
1. Right-click Remote Access Policies, and then click New Remote Access Policy.
2. In the New Remote Access Policy Wizard, click Next.
3. In the Policy name box, type Test Policy, and then click Next.
4. On the Access Method page, click Dial-up, and then click Next.
5. On the User or Group Access page, click User or Group, and then click Next. Note If you want to configure the remote access policy for a group, click Add, type the name of the group in the Enter Object Names To Select box, and then click OK.
6. On the Authentication Methods page, make sure that only the Microsoft Encrypted Authentication version 2 (MS-CHAPv2) check box is selected, and then click Next.
7. On the Policy Encryption Level page, click Next.
8. Click Finish. A new policy named Test Policy appears in the Remote Access Policies node.
9. In the right pane, right-click Test Policy, and then click Properties.
10. In the Test Policy Properties dialog box, make sure that Grant remote access permission is selected.
11. Click Edit Profile, click to select the Allow access only on these days and at these times check box, and then click Edit.
12. Click Denied, click Monday through Friday from 8:00 A.M. to 4:00 P.M., clickPermitted, and then click OK.
13. Click OK to close the Edit Dial-in Profile dialog box.
14. Click OK to close the Test Policy Properties dialog box. The Test Policy policy is in effect.
15. Repeat steps a through h to create another remote access policy named Test Block Policy.
16. In the right pane, right-click Test Block Policy, and then click Properties.
17. In the Test Block Policy Properties dialog box, click Deny remote access permission. The Test Block Policy policy is in effect.
Quit Routing and Remote Access.

How To Create a Roaming User Profile in Windows Server 2003

2010-02-04T16:19:00.002+08:00

Creating a roaming user profile is a two-step process. First you create a test user profile, and then you copy the test user profile to a network server.

Create a Test Profile

To create a test profile for the roaming user, follow these steps:

Log on as Administrator.
Click Start, point to Administrative Tools, and then click Computer Management.
In the console tree, expand Local Users and Groups, and then click Users.
Right-click Users, and then click New User.
Type a name and password for the user.
Click to clear User must change password at next logon.
Click Create, and then click Close.
Quit the Computer Management snap-in.
Log off the computer.
Log on as the test user account that you created in step 7. A user profile is automatically created on the local computer in the drive:\Documents and Settings\username folder (where drive is the drive on which Windows is installed).
Configure the desktop environment, including appearance, shortcuts, and Start menu options.
Log off, and then log on as Administrator.

Copy the Test Profile

To copy the test profile to a network server, follow these steps:

Create a folder on a network drive in which you can store network profiles. For example:
\\server_name\Profiles\user_name
Click Start, point to Control Panel, and then click System.
Click the Advanced tab, and then click Settings in the User Profiles section of theSystem Properties dialog box.
Under Profiles Stored On This Computer, click the profile for the user that you created in the “Create a Test Profile” section of this article, and then click Copy To.
In the Copy Profile To dialog box, type the network path to the folder.
Under Permitted to Use, click Change.
Type the name of the user account that you created in the “Create a Test Profile” section, and then click OK.
Click OK three times.
Click Start, point to Administrative Tools, and then click Computer Management.
In the console tree, expand Local Users and Groups, and then double-click Users.
Double-click the user account that you created in the “Create a Test Profile” section.
Click the Profile tab. In the Profile path box, type the path to the network profile folder. For example, type \\server_name\Profiles\user_name.
Click OK.
Quit the Computer Management snap-in.

NOTE: To make this profile mandatory, rename the Ntuser.dat file as Ntuser.man in the user’s profile folder.

NAT Configuration

2010-02-04T16:09:00.000+08:00

NAT can be configured in various ways. In the example below, the NAT router is configured to translate unregistered (inside, local) IP addresses, that reside on the private (inside) network, to registered IP addresses. This happens whenever a device on the inside with an unregistered address needs to communicate with the public (outside) network.

An ISP assigns a range of IP addresses to your company. The assigned block of addresses are registered, unique IP addresses and are called inside global addresses. Unregistered, private IP addresses are split into two groups. One is a small group (outside local addresses) that will be used by the NAT routers. The other, much larger group, known as inside local addresses, will be used on the stub domain. The outside local addresses are used to translate the unique IP addresses, known as outside global addresses, of devices on the public network.

IP addresses have different designations based on whether they are on the private network (stub domain) or on the public network (Internet), and whether the traffic is incoming or outgoing.

Most computers on the stub domain communicate with each other using the inside local addresses.
Some computers on the stub domain communicate a lot outside the network. These computers have inside global addresses, which means that they do not require translation.
When a computer on the stub domain that has an inside local address wants to communicate outside the network, the packet goes to one of the NAT routers.
The NAT router checks the routing table to see if it has an entry for the destination address. If it does, the NAT router then translates the packet and creates an entry for it in the address translation table. If the destination address is not in the routing table, the packet is dropped.
Using an inside global address, the router sends the packet on to its destination.
A computer on the public network sends a packet to the private network. The source address on the packet is an outside global address. The destination address is an inside global address.
The NAT router looks at the address translation table and determines that the destination address is in there, mapped to a computer on the stub domain.
The NAT router translates the inside global address of the packet to the inside local address, and sends it to the destination computer.

NAT overloading utilizes a feature of the TCP/IP protocol stack, multiplexing, that allows a computer to maintain several concurrent connections with a remote computer (or computers) using different TCP or UDP ports. An IP packet has a header that contains the following information:

Source Address - The IP address of the originating computer, such as 201.3.83.132
Source Port - The TCP or UDP port number assigned by the originating computer for this packet, such as Port 1080
Destination Address - The IP address of the receiving computer, such as 145.51.18.223
Destination Port - The TCP or UDP port number that the originating computer is asking the receiving computer to open, such as Port 3021

The addresses specify the two machines at each end, while the port numbers ensure that the connection between the two computers has a unique identifier. The combination of these four numbers defines a single TCP/IP connection. Each port number uses 16 bits, which means that there are a possible 65,536 (2¹⁶) values. Realistically, since different manufacturers map the ports in slightly different ways, you can expect to have about 4,000 ports available.

Dynamic NAT and Overloading

Here's how dynamic NAT works:

An internal network (stub domain) has been set up with IP addresses that were not specifically allocated to that company by IANA (Internet Assigned Numbers Authority), the global authority that hands out IP addresses. These addresses should be considered non-routable since they are not unique.
The company sets up a NAT-enabled router. The router has a range of unique IP addresses given to the company by IANA.
A computer on the stub domain attempts to connect to a computer outside the network, such as a Web server.
The router receives the packet from the computer on the stub domain.
The router saves the computer's non-routable IP address to an address translation table. The router replaces the sending computer's non-routable IP address with the first available IP address out of the range of unique IP addresses. The translation table now has a mapping of the computer's non-routable IP address matched with the one of the unique IP addresses.
When a packet comes back from the destination computer, the router checks the destination address on the packet. It then looks in the address translation table to see which computer on the stub domain the packet belongs to. It changes the destination address to the one saved in the address translation table and sends it to that computer. If it doesn't find a match in the table, it drops the packet.
The computer receives the packet from the router. The process repeats as long as the computer is communicating with the external system.

Here's how overloading works:

An internal network (stub domain) has been set up with non-routable IP addresses that were not specifically allocated to that company by IANA.
The company sets up a NAT-enabled router. The router has a unique IP address given to the company by IANA.
A computer on the stub domain attempts to connect to a computer outside the network, such as a Web server.
The router receives the packet from the computer on the stub domain.
The router saves the computer's non-routable IP address and port number to an address translation table. The router replaces the sending computer's non-routable IP address with the router's IP address. The router replaces the sending computer's source port with the port number that matches where the router saved the sending computer's address information in the address translation table. The translation table now has a mapping of the computer's non-routable IP address and port number along with the router's IP address.
When a packet comes back from the destination computer, the router checks the destination port on the packet. It then looks in the address translation table to see which computer on the stub domain the packet belongs to. It changes the destination address and destination port to the ones saved in the address translation table and sends it to that computer.
The computer receives the packet from the router. The process repeats as long as the computer is communicating with the external system.
Since the NAT router now has the computer's source address and source port saved to the address translation table, it will continue to use that same port number for the duration of the connection. A timer is reset each time the router accesses an entry in the table. If the entry is not accessed again before the timer expires, the entry is removed from the table.

In the next section we'll look at the organization of stub domains.

Stub Domains

Look at this table to see how the computers on a stub domain might appear to external networks.

Source Computer	Source Computer's IP Address	Source Computer's Port	NAT Router's IP Address	NAT Router's Assigned Port Number
A	192.168.32.10	400	215.37.32.203	1
B	192.168.32.13	50	215.37.32.203	2
C	192.168.32.15	3750	215.37.32.203	3
D	192.168.32.18	206	215.37.32.203	4

As you can see, the NAT router stores the IP address and port number of each computer in the address translation table. It then replaces the IP address with its own registered IP address and the port number corresponding to the location, in the table, of the entry for that packet's source computer. So any external network sees the NAT router's IP address and the port number assigned by the router as the source-computer information on each packet.
You can still have some computers on the stub domain that use dedicated IP addresses. You can create an access list of IP addresses that tells the router which computers on the network require NAT. All other IP addresses will pass through untranslated.
The number of simultaneous translations that a router will support are determined mainly by the amount of DRAM (Dynamic Random Access Memory) it has. But since a typical entry in the address-translation table only takes about 160 bytes, a router with 4 MB of DRAM could theoretically process 26,214 simultaneous translations, which is more than enough for most applications.
IANA has set aside specific ranges of IP addresses for use as non-routable, internal network addresses. These addresses are considered unregistered (for more information check out RFC 1918: Address Allocation for Private Internets, which defines these address ranges). No company or agency can claim ownership of unregistered addresses or use them on public computers. Routers are designed to discard (instead of forward) unregistered addresses. What this means is that a packet from a computer with an unregistered address could reach a registered destination computer, but the reply would be discarded by the first router it came to.
There is a range for each of the three classes of IP addresses used for networking:

Range 1: Class A - 10.0.0.0 through 10.255.255.255
Range 2: Class B - 172.16.0.0 through 172.31.255.255
Range 3: Class C - 192.168.0.0 through 192.168.255.255

Although each range is in a different class, your are not required to use any particular range for your internal network. It is a good practice, though, because it greatly diminishes the chance of an IP address conflict.

Security and Administration

Implementing dynamic NAT automatically creates a firewall between your internal network and outside networks, or between your internal network and the Internet. NAT only allows connections that originate inside the stub domain. Essentially, this means that a computer on an external network cannot connect to your computer unless your computer has initiated the contact. You can browse the Internet and connect to a site, and even download a file; but somebody else cannot latch onto your IP address and use it to connect to a port on your computer.
In specific circumstances, Static NAT, also called inbound mapping, allows external devices to initiate connections to computers on the stub domain. For instance, if you wish to go from an inside global address to a specific inside local address that is assigned to your Web server, Static NAT would enable the connection.

Static NAT (inbound mapping) allows a computer on the stub domain to maintain a specific address when communicating with devices outside the network.

Some NAT routers provide for extensive filtering and traffic logging. Filtering allows your company to control what type of sites employees visit on the Web, preventing them from viewing questionable material. You can use traffic logging to create a log file of what sites are visited and generate various reports from it.

NAT is sometimes confused with proxy servers, but there are definite differences between them. NAT is transparent to the source and to destination computers. Neither one realizes that it is dealing with a third device. But a proxy server is not transparent. The source computer knows that it is making a request to the proxy server and must be configured to do so. The destination computer thinks that the proxy server IS the source computer, and deals with it directly. Also, proxy servers usually work at layer 4 (transport) of the OSI Reference Model or higher, while NAT is a layer 3 (network) protocol. Working at a higher layer makes proxy servers slower than NAT devices in most cases.

NAT operates at the Network layer (layer 3) of the OSI Reference Model -- this is the layer that routers work at.

A real benefit of NAT is apparent in network administration. For example, you can move your Web server or FTP server to another host computer without having to worry about broken links. Simply change the inbound mapping at the router to reflect the new host. You can also make changes to your internal network easily, because the only external IP address either belongs to the router or comes from a pool of global addresses.
NAT and DHCP (dynamic host configuration protocol ) are a natural fit. You can choose a range of unregistered IP addresses for your stub domain and have the DHCP server dole them out as necessary. It also makes it much easier to scale up your network as your needs grow. You don't have to request more IP addresses from IANA. Instead, you can just increase the range of available IP addresses configured in DHCP to immediately have room for additional computers on your network.

Multi-homing

As businesses rely more and more on the Internet, having multiple points of connection to the Internet is fast becoming an integral part of their network strategy. Multiple connections, known as multi-homing, reduces the chance of a potentially catastrophic shutdown if one of the connections should fail.
In addition to maintaining a reliable connection, multi-homing allows a company to perform load-balancing by lowering the number of computers connecting to the Internet through any single connection. Distributing the load through multiple connections optimizes the performance and can significantly decrease wait times.
Multi-homed networks are often connected to several different ISPs (Internet Service Providers). Each ISP assigns an IP address (or range of IP addresses) to the company. Routers use BGP (Border Gateway Protocol), a part of the TCP/IP protocol suite, to route between networks using different protocols. In a multi-homed network, the router utilizes IBGP (Internal Border Gateway Protocol) on the stub domain side, and EBGP (External Border Gateway Protocol) to communicate with other routers.
Multi-homing really makes a difference if one of the connections to an ISP fails. As soon as the router assigned to connect to that ISP determines that the connection is down, it will reroute all data through one of the other routers.
NAT can be used to facilitate scalable routing for multi-homed, multi-provider connectivity. For more on multi-homing, see Cisco: Enabling Enterprise Multihoming.

How to Configure DCHP in Windows 2003 Server

2010-02-03T16:35:00.002+08:00

DHCP stands for Dynamic Host Configuration Protocol and it is designed for minimizing the Administration of the IP addresses in a big network. DHCP server can be setup with the appropriate and required settings in a computer network. A DHCP server can assign the IP address, gateway, DNS, DHCP, subnet mask, Router, Proxy server’s IP address from its predefined pool of the addresses. Once DHCP server has been configured, it automatically assigns the IP addresses to the client computers.

DHCP server holds a database of the IP addresses for a leased duration. Manual settings and changes in an enterprise network can be a nightmare. DHCP provides centralized control and management of your computer network.

Before your implement DHCP server in your network you need to review security issues, identify the range of the IP addresses, which you want to assign, determine the correct subnet mask, decide the duration of the leased addresses, identify the IP address of the router, gateway computer, DNS and WINS. This article will help you to setup and configure DHCP server in Windows 2003 Server.

In this Administrative tools of the Windows 2003 Sever perform the following actions.

Setup

* Click DHCP in the Administrative Tools or in the “Manager Your Servers” Window.
* In the Scope window, enter the scope name and description and click next.
* In the next window, you will be asked to define the range of the IP addresses that the scope will distribute to the network computers.
* Enter the start IP address, end IP address, length and subnet mask and click next.
* In the next Window, you will need to add exclusions i.e. you can add any IP addresses that you don’t want to be distributed to the network computers. After adding the range of the exclusive IP addresses click next. (You can assign the exclusive IP address manually to the company’s router, gateway or any other device. These IP addresses will not be distributed to the network computers.)
* In the next window, you need to enter the lease duration. It is recommended that you add longer lease duration for the fixed computer networks and the shorter leased time for the remote connections and Laptops.
* On the next screen, you will be given the choice to configure these options for the DHCP scope now or later. Check “Yes I want to configure these options now” and click next.
* On the next screen, you need to enter the Router’s IP address from the exclusive list, which we defined on the above steps. After you add the router’s address click next.
* In the next window, DNS settings can be entered i.e. IP address, domain name and server name.
* On the screen next to DNS, WINS server settings can be entered.
* On the next window, you need to activate the scope. Click “Yes I want to activate the scope now”.
* That’s all. You have successfully setup the DHCP in your Windows 2003 Server.

Configurations

After you have successfully setup the DHCP server, you may need to configure the multiple options based up the requirements of your network. For configuring the Exclusions after setting up the DHCP server, please follow the below steps.

In the DCHP main windows right click the Address Pool on the left side and click “Add Exclusions”. Here you can define the range of the IP addresses which you don’t want to distribute among the network computers.

If you want to reserve an IP address for a client computer, you can configure it by the following steps. For reserving the IP addresses for client computer, you need to know the MAC address of that client.

In the DHCP main window, right click Reservations in the left side. Provide the required parameters for fixing the IP addresses for the client computers.

You need to explore the various features of the DHCP server as you can configure multiple other options.

For Sale Slight Use Computer Hardware

2010-02-03T16:19:00.000+08:00

200 Gigabyte hardisk for only 1500 php
80 gigabyte Hardisk for only 1000php
40 gigabyte hardisk for only 800php

1gig ddr1 for only 1300php
1gig ddr2 for only 1000php

Restore Deleted IE7 With This Tips

2010-02-03T15:41:00.003+08:00

For IE 7 (maybe others)
Search file: regedit.exe
go to:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\HideDesktopIcons\NewStartPanel
double click the one starting with: 871C5380
Change value to: 0
Exit then press F5 once on desktop.
If you're using "Classic Menu"
Go to ClassicStartMenu instead of NewStartPanel

Classful IP Subnet Calculations

2010-02-03T15:15:00.002+08:00

Classful IP Subnet Calculations

1. IP Addressing

At this point you should know that IP, the Internet Protocol, is a network layer (OSI layer 3) protocol, used to route packets between hosts on different networks. To suit this purpose, IP must define an addressing scheme, so that a packet's intended destination can be indicated.
An IP address is composed of 32 bits. These 32 bits are divided into 4 octets of 8 bits each. You may have seen an IP address represented like this: 172.68.15.24. We must remember, however, that the computer understands this number only in binary, so we must often deal with them in binary. Many people are intimidated by this initially, but soon find that it is not difficult. If you do not allow yourself to be flustered, you can master this topic.
IP addresses are assigned to orginazations in blocks. Each block belongs to one of three classes: class A, class B, or class C. You can tell what class an IP address is by the value in its first octet.

Class A	1-126
Class B	128-191
Class C	192 -->

An IP address consists of two fields. The first field identifies the network, and the second field identifies the node on the network. Which bits of the address are in the network field and which bits are in the host field is determined by the subnet mask.
When a class A IP license is granted, you are assigned something like this: 99.0.0.0. Only the value of the bits in the first octet are assigned. This means you are free to assign any values you wish in the second, third and fourth octets.
The defualt subnet mask for a class A network is 255.0.0.0. High bits, ones, indicate the bits that are part of the network field of the IP address. The default subnet mask does not create subnets. Therefor, a class A network with the default subnet mask is one network. The three octets that are unassigned and unmasked are part of the host field of the address. There is a total of 24 bits in those three octets. Each bit can be in one of two states. Therefor, 2^24 is the number of host addresses that can be assigned on that network, almost. Two addresses are reserved on every network, x.x.x.0 and x.x.x.255. So the total number of hosts possible on this network is 2^24. 2^24-2=16,777,214 hosts for a class A IP network.
When a class B license is granted, the first two octets are assigned. For example, 172.198.x.x. The default subnet mask for a class B is 255.255.0.0. One network, two octets free, 16 bits for the host address field. 2^16-2=65,534 possible host addresses on a class B IP network.
When a class C license is granted, the first three octets are assigned, for example: 193.52.16.0. The default subnet mask for a class C is 255.255.255.0. Once octet makes up the host address field. 2^8-2=254 host addresses possible on a class C network.

2. Reason for Subnetting

We said that the default subnet mask for a class A IP network is 255.0.0.0. Once octet only of a class A network address identifies the network, with this subnet mask. This leaves three octets of 8 bits each, or 24 bits, to identify the host on that one network. 2^24=16,777,216 addresses. Two addresses are reserved, x.x.x.0 and x.x.x.255. 16,777,214 nodes can be assigned an IP address on this network.
It is highly unlikely that any organization would want one network of 16,777,214 nodes. They might want that many devices connected in a wide area network (WAN), thus capablee of communicating when neccessary, but they will want to subdivide this huge network into mostly self-contained subnetworks of nodes that communicate with each other often. This is called subnetting.
To understand why, consider what would happen in either a broadcast or a token passing network that consisted of over 16,000,000 nodes. Nothing would happen. It simply would not work. Though the problem is not as drastic, class B and class C IP networks are often subnetted, also.
The subnet mask is used to subdivide an IP network into subnets. This is a division that takes place in OSI layer 3, so it is a logical division that is created by the addressing scheme. This logical division is usually combined with a physical division. Many subnets are physically isolated from the rest of the network by a device such as a router or a switch. This aspect of subnetting is discussed in Unit 3--Data Link Layer.

3. How Subnetting Works

The bits of an address that are masked by the subnet mask are the bits that make up the network field of the address. To subnet, the default subnet mask for a network is extended to cover bits of the address that would otherwise be part of the host field. Once these bits are masked, they become part of the network field, and are used to identify subnets of the larger network.
Here is where we begin dealing with both addresses and subnetmasks in binary. Get yourself a cold beverage, stretch, take a deep breath and don't worry. Once you get your brain around the concepts, it is not difficult. You just have to keep trying until the light goes on.

3.1 Translating Binary to Decimal

Both IP addresses and subnet masks are composed of 32 bits divided into 4 octets of 8 bits each. Here is how a single octet translates from binary to decimal. Consider an octet of all ones: 11111111.

128   64   32   16   8   4   2   1
---   --   --   --   -   -   -   -
 1     1    1    1   1   1   1   1 
128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255

Here's another: 10111001

128   64   32   16   8   4   2   1
---   --   --   --   -   -   -   -
 1     0    1    1   1   0   0   1
128 +  0 + 32  +16 + 8 + 0 + 0 + 1 = 185

and 00000000

128   64   32   16   8   4   2   1
---   --   --   --   -   -   -   -
 0     0    0    0   0   0   0   0
 0  +  0 +  0 +  0 + 0 + 0 + 0 + 0 = 0

3.2 Converting Decimal to Binary

Converting decimal to binary is similar. Consider 175:

128   64   32   16   8   4   2   1
---   --   --   --   -   -   -   -
 1     0    1    0   1   1   1   1
128 +  0 + 32 +  0 + 8 + 4 + 2 + 1 = 175

175=10101111

3.3 Simple Subnetting

The simpliest way to subnet is to take the octet in the subnet mask that covers the first unassigned octet in the IP address block, and make all its bits high. Remember, a high bit, a 1, in the subnet mask indicates that that corresponding bit in the IP address is part of the network field. So, if you have a class B network 172.160.0.0, with the subnet mask 255.255.0.0, you have one network with 65, 534 possible addresses. If you take that subnet mask and make all the bits in the third octet high

128   64   32   16   8   4   2   1
---   --   --   --   -   -   -   -
 1     1    1    1   1   1   1   1
128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255

you get the subnet mask 255.255.255.0.

172.60.  0. 0
255.255.255.0

Now the third octet of all the addresses on this network are part of the network field instead of the host field. That is one octet, or eight bits, that can be manipulated to create subnets. 2^8=256 possible subnets now on this class B network.
One octet is left for the host field. 2^8-2=254 possible host addressed on each subnet.

3.4 Advanced Subnetting

That is the simplist way to subnet, but it may not be the most desirable. You might not want 254 subnets on your class B network. Instead, you might use a subnet mask like 255.255.224.0. How many subnets would this give you? The first step is to see how many bits are allocated to the network by this mask.

128   64   32   16   8   4   2   1
---   --   --   --   -   -   -   -
 1     1    1    0   0   0   0   0
128 + 64 + 32 +  0 + 0 + 0 + 0 + 0 = 224

3 bits are allocated. 2^3=8 subnets.
How many hosts on each subnet? Well, 5 bits from this octet are left for the host field, and 8 bits in the fourth octet, for a total of 13 bits in the host field. 2^13-2=8190 possible hosts on each subnet.
The subnet mask is always extended by masking off the next bit in the address, from left to right. Thus, the last octet in the subnet mask will always be one of these: 128, 192, 224, 240, 248, 252, 254 or 255.
Given the IP address of a host and the subnet address for the network, you need to be able to calculate which subnet that host is on. To do this we compare the binary representation of the pertinent octet of the subnet mask witht he binary representation of the corresponding octet in the IP address. Example:

IP address=172.60.50.2
subnet mask=255.255.224.0

50= 00110010
224=11100000

We perform a logical on these two numbers. We will be left with only the bits where there is a one in both octets.

00110010
11100000
--------
00100000=32

This host is on subnet 172.60.32.0.
We also need to be able to find the range of assignable IP addresses on this subnet. To do this, we take the binary that tells us the subnet address, in this case 00100000, and compare it with the subnet mask.

00100000
11100000

The bits convered by the mask we will leave as they are. The rest of the bits we make high. So

00100000
11100000
--------
0011111=63

The range of assignable IP addresses on the subnet 172.60.32.0 is 172.60.32.1-172.60.63.254.
On every network and subnet, two addresses are reserved. At the low end of the range of addresses for the network or subnet, in this case 172.60.64.0, is the address for the network or subnet itself. The address at the high end of the range of addresses, in this case 172.60.95.255, is the broadcast address. Any message sent to the broadcast address will be received by every host on the network.

4. Sample Problem

Here is a sample problem for you to calculate. When you are done, you can check your answers using an online subnet calcualtor at Tactix Engineering.

IP address:  154.16.52.16
subnet mask:  255.255.240.0

Find:
Number of subnets possible on this network:
Number of hosts possible on each subnet:
Which subnet this address is on:
Range of addresses on that subnet:

Cisco T1 Load Balancing HOWTO

2010-02-03T15:14:00.000+08:00

This document is for those facing the common problem of using Cisco routers to load balance 2 or more parallel T1's.

Acknowledgments

Thanks to Mark Costlow who showed me how this works.
References to pertinent Cisco documentation can be found at the end of this document.

1. What This Document covers

This document is for those facing the common problem of using Cisco routers to load balance IP traffic across 2 or more parallel T1's. Although the problem is common, acquiring the knowledge to address the issue can be frustratingly difficult. Hopefully this will help.

2. Per-Packet Load Balancing

What you want if you can get it, and if it will not break any of your applications, is per-packet load balancing. Load balancing on a router happens at layer 3, meaning it is a function of IP routing. Per-packet load balancing means the Cisco will route outbound IP packets in round-robin fashion, simply taking turns which interface it routes each IP packet out. Per-packet load balancing gives the most even distribution across outbound connections.

3. Annoying Fact #1 Outbound Only

A router can load balance outbound traffic only. In order to get load balancing in both directions, the T1's on Router A must both terminate on the same Router B. Load balancing must be configured on both Router A and Router B. Easy enough if Router A and Router B are both in your control. If they are not, you will have to coordinate with the authority that controls the other router. Another unfortunate result is that per-packet load balancing on T1's to multiple ISP's is not feasible.

4. Annoying Fact #2 Out of Order Packets

This method of per-packet load balancing can mean that packets in a particular connection or flow arrive at their destination out of sequence. This doesn't cause a problem for most applications, but it can cause problems for the increasingly popular streaming media, both video and audio. This includes voice over IP.
If out of order packets will cause you a problem, Cisco recommends using Multilink PPP to do your load balancing. I do not personally have experience with MLPPP between Cisco routers.

5. Cisco Express Forwarding

Cisco Express Forwarding (CEF) is one method that IOS can use to switch packets through the router. It is the method Cisco recommends, and seems to be the right thing most of the time. It is required for the per-packet load balancing this document discusses. You can tell if CEF is enabled by issuing the command:
show ip cef
If it is enabled you get some interesting output. If it is not enabled, IOS will tell you that it is not running. To enable CEF, in global configuration mode:
ip cef

6. Equal Cost Routes

To get load balancing to happen, you need equal cost routes pointing to the interfaces involved in the load balancing. For example, on Router A load balancing 2 T1's, the show ip route output might include something like this:

S*   0.0.0.0/0 is directly connected, Serial0/1
               is directly connected, Serial0/0

And on Router B the show ip route output might include something like this:

ip route 192.168.8.0 255.255.255.0 Serial1/3 10
ip route 192.168.8.0 255.255.255.0 Serial1/0 10

7. ip load-sharing per-packet

The magic IOS command you have been looking for but couldn't find on Cisco's website is:
ip load-sharing per-packet
You apply this to each interface you want to participate in per-packet load balancing. Remember, you want to do this on the routers at both ends of the T1's.
My experience is that this works like a charm. Graphs I look at everyday of traffic on T1's configured this way are indistinguishable from each other. The balancing is near perfect.

8. References

Per-Packet Load Balancing
Alternatives for High Bandwidth Connections Using Parallel T1/E1 Links

9. More Information

<!-- Cisco Router Configuration Tutorial
My tutorial on IP subnet calculations
And More ...

Cisco Router Configuration Tutorial Using CLI

2010-02-03T15:08:00.000+08:00

This document covers basic Cisco router IP configuration using the command-line interface

Acknowledgments
The following sources where extremely useful:

Leinwand, Pinsky, and Culpepper. Cisco Router Configuration. Indianapolis, Indiana: Cisco Press, 1998.
Cisco Systems, Inc., http://www.cisco.com

Disclaimer
This document carries no explicit or implied warranty. Nor is there any guarantee that the information contained in this document is accurate. It is offered in the hopes of helping others, but you use it at your own risk. The author will not be liable for any damages that occur as a result of using this document.
Conventions
Important terms and concepts, when they are introduced, may be displayed in bold. Commands included in the body of the text will be displayed in this font. All names and addresses used in examples are just that, examples, and should not be used on your network. Do not type them in verbatim when configuring your system. Finally, in some examples where the command rquires an IP address as an argument, the IP address may be represented in this way, xx.xx.xx.xx, or aa.bb.cc.dd. You will never actually use these strings when configuring your system. They are mearly a convention of this document to specify that you should substitute the appropriate IP address at that point.

1. What this document covers

There are several methods available for configuring Cisco routers. It can be done over the network from a TFTP server. It can be done through the menu interface provided at bootup, and it can be done from the menu interface provided by using the command setup. This tutorial does not cover these methods. It covers configuration from the IOS command-line interface only. Useful for anyone new to Cisco routers, and those studying for CCNA.
Note that this tutorial does not cover physically connecting the router to the networks it will be routing for. It covers operating system configuration only.

1.1 Reasons for using the command-line

The main reason for using the command-line interface instead of a menu driven interface is speed. Once you have invested the time to learn the command-line commands, you can perform many operations much more quickly than by using a menu. This is basically true of all command-line vs. menu interfaces. What makes it especially efficient to learn the command-line interface of the Cisco IOS is that it is standard across all Cisco routers. Also, some questions on the CCNA exam require you to know command-line commands.

2. Getting started with Cisco

Initially you will probably configure your router from a terminal. If the router is already configured and at least one port is configured with an IP address, and it has a physical connection to the network, you might be able to telnet to the router and configure it across the network. If it is not already configured, then you will have to directly connect to it with a terminal and a serial cable. With any Windows box you can use Hyperterminal to easily connect to the router. Plug a serial cable into a serial (COM) port on the PC and the other end into the console port on the Cisco router. Start Hyperterminal, tell it which COM port to use and click OK. Set the speed of the connection to 9600 baud and click OK. If the router is not on, turn it on.
If you wish to configure the router from a Linux box, either Seyon or Minicom should work. At least one of them, and maybe both, will come with your Linux distribution.
Often you will need to hit the Enter key to see the prompt from the router. If it is unconfigured it will look like this:
Router> If it has been previously configured with a hostname, it will look like this:
hostname of router> If you have just turned on the router, after it boots it will ask you if you wish to begin initial configuration. Say no. If you say yes, it will put you in the menu interface. Say no.

2.1 Modes

The Cisco IOS command-line interface is organized around the idea of modes. You move in and out of several different modes while configuring a router, and which mode you are in determines what commands you can use. Each mode has a set of commands available in that mode, and some of these commands are only available in that mode. In any mode, typing a question mark will display a list of the commands available in that mode.
Router>?

2.2 Unprivileged and privileged modes

When you first connect to the router and provide the password (if necessary), you enter EXEC mode, the first mode in which you can issue commands from the command-line. From here you can use such unprivileged commands as ping, telnet, and rlogin. You can also use some of the show commands to obtain information about the system. In unprivileged mode you use commands like, show version to display the version of the IOS the router is running. Typing show ? will diplay all the show commands available in the mode you are presently in.
Router>show ? You must enter privileged mode to configure the router. You do this by using the command enable. Privileged mode will usually be password protected unless the router is unconfigured. You have the option of not password protecting privileged mode, but it is HIGHLY recommended that you do. When you issue the command enable and provide the password, you will enter privileged mode.
To help the user keep track of what mode they are in, the command-line prompt changes each time you enter a different mode. When you switch from unprivileged mode to privileged mode, the prompt changes from:
Router> to
Router# This would probably not be a big deal if there were just two modes. There are, in fact, numerous modes, and this feature is probably indispensable. Pay close attention to the prompt at all times.
Within privileged mode there are many sub-modes. In this document I do not closely follow Cisco terminology for this hierarchy of modes. I think that my explanation is clearer, frankly. Cisco describes two modes, unprivileged and privileged, and then a hierarchy of commands used in privileged mode. I reason that it is much clearer to understand if you just consider there to be many sub-modes of privileged mode, which I will also call parent mode. Once you enter privileged mode (parent mode) the prompt ends with a pound sign (#). There are numerous modes you can enter only after entering privileged mode. Each of these modes has a prompt of the form:
Router(arguments)# They still all end with the pound sign. They are subsumed within privileged mode. Many of these modes have sub-modes of their own. Once you enter priliged mode, you have access to all the configuration information and options the IOS provides, either directly from the parent mode, or from one of its submodes.

3. Configuring your Cisco Router

If you have just turned on the router, it will be completely unconfigured. If it is already configured, you may want to view its current configuration. Even if it has not been previously configured, you should familiarize yourself with the show commands before beginning to configure the router. Enter privileged mode by issuing the command enable, then issue several show commands to see what they display. Remember, the command show ? will display all the showcommands aavailable in the current mode. Definately try out the following commands:

   Router#show interfaces

Router#show ip protocols

Router#show ip route

Router#show ip arp

When you enter privileged mode by using the command enable, you are in the top-level mode of privileged mode, also known in this document as "parent mode." It is in this top-level or parent mode that you can display most of the information about the router. As you now know, you do this with the show commands. Here you can learn the configuration of interfaces and whether they are up or down. You can display what IP protocols are in use, such as dynamic routing protocols. You can view the route and ARP tables, and these are just a few of the more important options.
As you configure the router, you will enter various sub-modes to set options, then return to the parent mode to display the results of your commands. You also return to the parent mode to enter other sub-modes. To return to the parent mode, you hit ctrl-z. This puts any commands you have just issued into affect, and returns you to parent mode.

3.1 Global configuration (config)

To configure any feature of the router, you must enter configuration mode. This is the first sub-mode of the parent mode. In the parent mode, you issue the command config.

   Router#config

Router(config)#

As demonstrated above, the prompt changes to indicate the mode that you are now in.
In connfiguration mode you can set options that apply system-wide, also refered to as "global configurations." For instance, it is a good idea to name your router so that you can easily identify it. You do this in configuration mode with the hostname command.

   Router(config)#hostname ExampleName

ExampleName(config)#

As demonstrated above, when you set the name of the host with the hostname command, the prompt immediately changes by replacing Router with ExampleName. (Note: It is a good idea to name your routers with an organized naming scheme.)
Another useful command issued from config mode is the command to designate the DNS server to be used by the router:

   ExampleName(config)#ip name-server aa.bb.cc.dd

ExampleName(config)#ctrl-Z

ExampleName#

This is also where you set the password for privileged mode.

   ExampleName(config)#enable secret examplepassword

ExampleName(config)#ctrl-Z

ExampleName#

Until you hit ctrl-Z (or type exit until you reach parent mode) your command has not been put into affect. You can enter config mode, issue several different commands, then hit ctrl-Z to activate them all. Each time you hit ctrl-Z you return to parent mode and the prompt:
ExampleName# Here you use show commands to verify the results of the commands you issued in config mode. To verify the results of the ip name-server command, issue the command show host.

3.2 Configuring Cisco router interfaces

Cisco interface naming is straightforward. Individual interfaces are referred to by this convention:
media type slot#/port# "Media type" refers to the type of media that the port is an interface for, such as Ethernet, Token Ring, FDDI, serial, etc. Slot numbers are only applicable for routers that provide slots into which you can install modules. These modules contain several ports for a given media. The 7200 series is an example. These modules are even hot-swapable. You can remove a module from a slot and replace it with a different module, without interrupting service provided by the other modules installed in the router. These slots are numbered on the router.
Port number refers to the port in reference to the other ports in that module. Numbering is left-to-right, and all numbering starts at 0, not at one.
For example, a Cisco 7206 is a 7200 series router with six slots. To refer to an interface that is the third port of an Ethernet module installed in the sixth slot, it would be interface ethernet 6/2. Therefor, to display the configuration of that interface you use the command:
ExampleName#show interface ethernet 6/2 If your router does not have slots, like a 1600, then the interface name consists only of:
media type port# For example:
ExampleName#show interface serial 0 Here is an example of configuring a serial port with an IP address:

   ExampleName#config

ExampleName(config)#interface serial 1/1

ExampleName(config-if)#ip address 192.168.155.2 255.255.255.0

ExampleName(config-if)#no shutdown

ExampleName(config-if)#ctrl-Z

ExampleName#

Then to verify configuration:
ExampleName#show interface serial 1/1 Note the no shutdown command. An interface may be correctly configured and physically connected, yet be "administratively down." In this state it will not function. The command for causing an interface to be administratively down is shutdown.

   ExampleName(config)#interface serial 1/1

ExampleName(config-if)#shutdown

ExampleName(config-if)#ctrl-Z

ExampleName#show interface serial 1/1

In the Cisco IOS, the way to reverse or delete the results of any command is to simply put no infront of it. For instance, if we wanted to unassign the IP address we had assigned to interface serial 1/1:

   ExampleName(config)#interface serail 1/1

ExampleName(config-if)#no ip address 192.168.155.2 255.255.255.0

ExampleName(config-if)ctrl-Z

ExampleName#show interface serial 1/1

Configuring most interfaces for LAN connections might consist only of assigning a network layer address and making sure the interface is not administratively shutdown. It is usually not necessary to stipulate data-link layer encapsulation. Note that it is often necessary to stipulate the appropriate data-link layer encapsulation for WAN connections, such as frame-relay and ATM. Serial interfaces default to using HDLC. A discussion of data-link protocols is outside the scope of this document. You will need to look up the IOS command encapsulation for more details.

3.3 Configuring Cisco Routing

IP routing is automatically enabled on Cisco routers. If it has been previously disabled on your router, you turn it back on in config mode with the command ip routing.

   ExampleName(config)#ip routing

ExampleName(config)#ctrl-Z

There are two main ways a router knows where to send packets. The administrator can assign static routes, or the router can learn routes by employing a dynamic routing protocol.
These days static routes are generally used in very simple networks or in particular cases that necessitate their use. To create a static route, the administrator tells the router operating system that any network traffic destined for a specified network layer address should be forwarded to a similiarly specified network layer address. In the Cisco IOS this is done with the ip route command.

   ExampleName#config

ExampleName(config)#ip route 172.16.0.0 255.255.255.0 192.168.150.1

ExampleName(config)#ctrl-Z

ExampleName#show ip route

Two things to be said about this example. First, the packet destination address must include the subnet mask for that destination network. Second, the address it is to be forwarded to is the specified addres of the next router along the path to the destination. This is the most common way of setting up a static route, and the only one this document covers. Be aware, however, that there are other methods.
Dynamic routing protocols, running on connected routers, enable those routers to share routing information. This enables routers to learn the routes available to them. The advantage of this method is that routers are able to adjust to changes in network topologies. If a route is physically removed, or a neighbor router goes down, the routing protocol searches for a new route. Routing protocols can even dynamically choose between possible routes based on variables such as network congestion or network reliability.
There are many different routing protocols, and they all use different variables, known as "metrics," to decide upon appropriate routes. Unfortunately, a router needs to be running the same routing protocols as its neighbors. Many routers can, however, run mutliple protocols. Also, many protocols are designed to be able to pass routing information to other routing protocols. This is called "redistribution." The author has no experience with trying to make redistribution work. There is an IOS redistribute command you can research if you think this is something you need. This document's compagnion case study describes an alternative method to deal with different routing protocols in some circumstances.
Routing protocols are a complex topic and this document contains only this superficial description of them. There is much to learn about them, and there are many sources of information about them available. An excelent source of information on this topic is Cisco's website, http://www.cisco.com.
This document describes how to configure the Routing Information Protocol (RIP) on Cisco routers. From the command-line, we must explicitly tell the router which protocol to use, and what networks the protocol will route for.

   ExampleName#config

ExampleName(config)#router rip

ExampleName(config-router)#network aa.bb.cc.dd

ExampleName(config-router)#network ee.ff.gg.hh

ExampleName(config-router)#ctrl-Z

ExampleName#show ip protocols

Now when you issue the show ip protocols command, you should see an entry describing RIP configuration.

3.4 Saving your Cisco Router configuration

Once you have configured routing on the router, and you have configured individual interfaces, your router should be capable of routing traffic. Give it a few moments to talk to its neighbors, then issue the commands show ip route and show ip arp. There should now be entries in these tables learned from the routing protocol.
If you turned the router off right now, and turned it on again, you would have to start configuration over again. Your running configuration is not saved to any perminent storage media. You can see this configuration with the command show running-config.
ExampleName#show running-config You do want to save your successful running configuration. Issue the command copy running-config startup-config.
ExampleName#copy running-config startup-config Your configuration is now saved to non-volatile RAM (NVRAM). Issue the command show startup-config.
ExampleName#show startup-config Now any time you need to return your router to that configuration, issue the command copy startup-config running-config.
ExampleName#copy startup-config running-config

3.5 Example Cisco Router configuration

4. Troubleshooting your Cisco router

Inevitably, there will be problems. Usually, it will come in the form of a user notifying you that they can not reach a certain destination, or any destinattion at all. You will need to be able to check how the router is attempting to route traffic, and you must be able to track down the point of failure.
You are already familiar with the show commands, both specific commands and how to learn what other show commands are available. Some of the most basic, most useful commands you will use for troubleshooting are:

   ExampleName#show interfaces

ExampleName#show ip protocols

ExampleName#show ip route

ExampleName#show ip arp

5. References

Router to Any Devices RollOver Cable Color Coding

2010-02-03T12:43:00.000+08:00

Straight-Through Ethernet Cable

2010-02-03T12:41:00.000+08:00

CrossOver Ethernet Cable Color Coding

2010-02-03T12:39:00.000+08:00

CCNA 1 Chapter 3 V4.0 Answers

2010-02-03T12:07:00.000+08:00

CCNA Discovery 4.1 - CCNA Discovery Answers
http://Net-Maker.blogspot.com/
CCNA 1 Chapter 3 V4.0
Labels: CCNA 1 Chapter 3 V4.0

1) Which term is used to describe the process of placing one message format into
another format so that the message can be delivered across the appropriate medium?
flow control
* encapsulation
encoding
multicasting
access method
2)
Refer to the graphic. Five PCs are connected through a hub. If host H1 wants to reply
to a message from host H2, which statement is true?
CCNA Discovery 4.1 - CCNA Discovery Answers
http://ccna-discovery-4.blogspot.com/
* H1 sends a unicast message to H2, but the hub forwards it to all devices.
H1 sends a unicast message to H2, and the hub forwards it directly to H2.
H1 sends a broadcast message to H2, and the hub forwards it to all devices.
H1 sends a multicast message to H2, and the hub forwards it directly to H2.
3) Which two statements concerning networking standards are true? (Choose two.)
adds complexity to networks
encourages vendors to create proprietary protocols
* provides consistent interconnections across networks
ensures that communications work best in a single-vendor environment
* simplifies new product development
4) What does the 100 mean when referencing the 100BASE-T Ethernet standard?
type of cable used
type of data transmission
* speed of transmission
type of connector required
maximum length of cable allowed
5) Which address does an NIC use when deciding whether to accept a frame?
source IP address
source MAC address
destination IP address
* destination MAC address
source Ethernet address
6) Which type of address is used in an Ethernet frame header?
logical addresses only
IP addresses only
* MAC addresses only
broadcast addresses only
7) hat is the function of the FCS field in an Ethernet frame?
* detects transmission errors
provides timing for transmission
contains the start of frame delimiter
indicates which protocol will receive the frame
8) What is the purpose of logical addresses in an IP network?
They identify a specific NIC on a host device.
They are used to determine which host device accepts the frame.
They provide vendor-specific information about the host.
* They are used to determine the network that the host is located on.
They are used by switches to make forwarding decisions.
9) Which device accepts a message on one port and always forwards the message to
all other ports?
modem
CCNA Discovery 4.1 - CCNA Discovery Answers
http://ccna-discovery-4.blogspot.com/
switch
router
* hub
10) Which two networking devices are used to connect hosts to the access layer?
(Choose two.)
router
* hub
* switch
server
computer
11) Host A needs to learn the MAC address of Host B, which is on the same LAN
segment. A message has been sent to all the hosts on the segment asking for the MAC
address of Host B. Host B responds with its MAC address and all other hosts
disregard the request. What protocol was used in this scenario?
* ARP
DHCP
DNS
WINS
12) A switch receives a frame with a destination MAC address that is currently not in
the MAC table. What action does the switch perform?
It drops the frame.
It sends out an ARP request looking for the MAC address.
* It floods the frame out of all active ports, except the origination port.
It returns the frame to the sender.
13) What is a benefit of having a router within the distribution layer?
prevents collisions on a local network
* keeps broadcasts contained within a local network
controls which hosts have access to the network
controls host-to-host traffic within a single local network
14)
Refer to the graphic. What does the router do after it determines that a data packet
CCNA Discovery 4.1 - CCNA Discovery Answers
http://ccna-discovery-4.blogspot.com/
from Network 1 should be forwarded to Network 2?
It sends the data packet as it was received.
* It reassembles the frame with different MAC addresses than the original frame.
It reassembles the data packet with different IP addresses than the original data
packet.
It reassembles both the packet and the frame with different destination IP and MAC
addresses.
15) Which table does a router use to make decisions on where a data packet is to be
sent?
ARP table
* routing table
network table
forwarding table
16) If the default gateway is configured incorrectly on the host, what is the impact on
communications?
The host is unable to communicate on the local network.
* The host can communicate with other hosts on the local network, but is unable to
communicate with hosts on remote networks.
The host can communicate with other hosts on remote networks, but is unable to
communicate with hosts on the local network.
There is no impact on communications.
17) What device is typically used as the default gateway for a computer?
a server hosted by the ISP
* the router interface closest to the computer
a server managed by a central IT department
the switch interface that connects to the computer
18) If a router receives a packet that it does not know how to forward, what type of
route must be configured on the router to prevent the router from dropping it?
dynamic route
* default route
destination route
default destination
19) Which two items are included in a network logical map? (Choose two.)
* naming scheme
* IP addressing scheme
length of cable runs
physical location of networking devices
specific layout of interconnections between networking devices and hosts
20) An integrated router can normally perform the functions of which two other
network devices? (Choose two.)
NIC
* switch
CCNA Discovery 4.1 - CCNA Discovery Answers
http://ccna-discovery-4.blogspot.com/
e-mail server
application server
* wireless access point
21) What is a reason for disabling simple file sharing?
It enables the user to map a remote resource with a local drive.
It enables the user to share all files with all users and groups.
It enables the user to share printers.
* It enables the user to set more specific security access levels.

CCNA 1 Chapter 2 V4.0 Answers

2010-02-03T12:02:00.000+08:00

CCNA Discovery 4.1 - CCNA Discovery Answers
http://Net-Maker.blogspot.com/
CCNA 1 Chapter 2 V4.0
Labels: CCNA 1 Chapter 2 V4.0

1) An operating system is severely damaged. All data on the partition needs to be
deleted, and all application software must be reinstalled. Which installation method
should be used to correct the problem?
* clean install
upgrade
multi-boot
virtualization
2) Which two statements should be included in a pre-installation checklist when
upgrading an operating system? (Choose two.)
Verify that the hardware resources have multiple partitions.
* Verify that the hardware resources meet or exceed the published minimum
requirements.
* Complete a full backup of all important files and data.
Overwrite any data currently contained on the drive to remove all contents.
Verify that the hardware resources are certified to work with the existing operating
system prior to upgrading.
3) Which three pieces of information must be specified on a computer to allow that
computer to send and receive information across networks? (Choose three.)
closest server
operating system
* IP address
* subnet mask
* default gateway
network card driver
4) Which two items must be unique to each computer and cannot be duplicated on a
network? (Choose two.)
partition
file system
* computer name
* IP address
operating system
5) Which method of interacting with an operating system involves typing commands
at a command prompt?
* CLI
GUI
redirector
kernel translator
6) What are three characteristics of an operating system that is released under the GPL
(GNU Public License)? (Choose three.)
* full access to source code
CCNA Discovery 4.1 - CCNA Discovery Answers
http://ccna-discovery-4.blogspot.com/
* software often available free
structured development cycle
can be expensive to purchase
limits what end-user can do with code
* support normally user-based and often free
7) What is the purpose of a default gateway?
physically connects a computer to a network
provides a permanent address to a computer
identifies the network to which a computer is connected
identifies the logical address of a networked computer and uniquely identifies it to the
rest of the network
* identifies the device that allows local network computers to communicate with
devices on other networks
8) Which two statements are true about drive partitions? (Choose two.)
* Partitions are necessary in multi-boot installations.
* A hard drive can be divided into an operating system partition and a data partition.
User data is never overwritten when a drive is partitioned.
A disk partition is a defined section of an operating system.
Each partition requires a different file system type.
9) What occurs when computers are configured to receive their network
configurations dynamically?
Each computer receives a permanent IP address.
A network administrator enters information on each computer.
* Each computer requests configuration information from a server.
An NIC automatically provides configuration information to the computer and stores
that configuration information.
10) What are two ways that a user can interact with an operating system shell?
(Choose two.)
* CLI
OS
* GUI
NIC
kernel
11) Which three resource specifications are given by the manufacturer to ensure that
an operating system performs as designed? (Choose three.)
* required hard disk space
type of accelerated graphics card
* recommended amount of RAM
printer requirements
* processor type and speed
type of keyboard

CCNA 1 Chapter 1 V4.0 Answers

2010-02-03T11:58:00.000+08:00

CCNA Discovery 4.0 - CCNA Discovery Answers
http://Net-Maker.blogspot.com/
CCNA 1 Chapter 1 V4.0
Labels: CCNA 1 Chapter 1 V4.0

1. Which computer component is considered the nerve center of the computer system
and is responsible for processing all of the data within the machine?
RAM
* CPU
video card
sound card
operating system
2. What are two advantages of purchasing a preassembled computer? (Choose two..
* usually a lower cost
exact components may be specified
extended waiting period for assembly
* adequate for performing most general applications
suited for customers with special needs
3. A user plans to run multiple applications simultaneously on a computer. Which
computer component is essential to accomplish this?
* RAM
NIC
video card
sound card
storage device
4. Which adapter card enables a computer system to exchange information with other
systems on a local network?
modem card
controller card
video card
sound card
* network interface card
5. What is the main storage drive used by servers, desktops, and laptops?
tape drive
* hard drive
optical drive (DVD)
floppy disk drive
6. Which component is designed to remove high-voltage spikes and surges from a
power line so that they do not damage a computer system?
CPU
* surge suppressor
motherboard
hard drive
7. What are two examples of output peripheral devices? (Choose two.)
CCNA Discovery 4.1 - CCNA Discovery Answers
http://ccna-discovery-4.blogspot.com/
* printer
* speakers
flash drive
external DVD
external modem
8. What two functions does a UPS provide that a surge protector does not ? (Choose
two.)
protects the computer from voltage surges
* provides backup power from an internal battery
protects the computer from sudden voltage spikes
gives the user time to phone the electrical company
* gives the user time to safely shut down the computer if the power fails
provides backup power through a generator provided by the wall outlet
9. What is a word processor?
It is a physical computer component.
* It is a program designed to perform a specific function.
It is a program that controls the computer resources.
It is a functional part of an operating system.
10. What is the purpose of the ASCII code?
translates bits into bytes
interprets graphics digitally
translates digital computer language into binary language
* represents letters, characters, and numbers with bits
11. Why do servers often contain duplicate or redundant parts?
Servers require more power and thus require more components.
* Servers should be accessible at all times.
Servers can be designed as standalone towers or rack mounted.
Servers are required by networking standards to have duplicate parts.
12. What are two benefits of hooking up a laptop to a docking station? (Choose two.)
Mobility is increased.
* An external monitor can be used.
* Alternate connectivity options may be available.
The keyboard can be changed to a QWERTY-style keyboard.
More wireless security options are available.
13. Applications can be grouped into general use software or industry specific
software. What are two examples of industry specific software? (Choose two.)
* CAD
presentation
spreadsheet
word processing
* medical practice management
contacts/scheduling management
CCNA Discovery 4.1 - CCNA Discovery Answers
http://ccna-discovery-4.blogspot.com/
14. Which three terms describe different types of computers? (Choose three.)
operating system
network
* laptop
* desktop
Windows
* mainframe
15. How is a server different from a workstation computer?
The server works as a standalone computer.
* The server provides services to clients.
The workstation has fewer applications installed.
The workstation has more users who attach to it.
16. How many values are possible using a single binary digit?
1
* 2
4
8
9
16
17. What measurement is commonly associated with computer processing speed?
bits
pixels
* hertz
bytes
18. What can be used to prevent electrostatic discharge (ESD)?
dry and non humid conditions
carpeted floor
* grounding strap
uncluttered work space
19. If a peripheral device is not functioning, what are three things you should do to
solve the problem? (Choose three.)
* Use the testing functionality on the peripheral itself, if available.
* Verify that all cables are connected properly.
Disconnect all cables connected to the computer except those connected to the
peripheral.
* Ensure that the peripheral is powered on.
Disconnect the peripheral and verify that the computer is operating normally.
Reload the computer operating system.
20. Which two steps should be performed when installing a peripheral device?
(Choose two.)
CCNA Discovery 4.1 - CCNA Discovery Answers
http://ccna-discovery-4.blogspot.com/
* Download and install the most current driver.
Connect the peripheral using any cable and any available port on the computer.
* Connect the peripheral using an appropriate cable or wireless connection.
Test the peripheral on another machine before installing it on the one where it will be
used.
Check the computer documentation to see if the peripheral vendor is compatible with
the PC vendor.
21. In newer operating systems, how are system resources assigned by default when
components are installed?
manually assigned by the operating system
manually assigned by the administrator
statically assigned by the component to a preset resource
* dynamically assigned between the component and the operating system