Lab 15.2: Troubleshooting Network Protocols

Often you will need to verify the installation of a protocol or troubleshoot connectivity between computers. TCP/IP comes with a number of utilities to allow you to verify the configuration and troubleshoot connectivity.

This lab will cover the use of four key commands that you can use to verify configuration and troubleshoot connectivity issues. You use WINIPCFG in Windows 98 and IPCONFIG in Windows 2000/XP to display the current TCP/IP configuration. You will be able to see the IP address, subnet mask, default gateway, DNS servers, and hardware address. Additional switches or buttons allow you to release and renew the information if you are using DHCP.

The next command is PING. It is used to verify connectivity between two computers. You can use this command to isolate where a breakdown of connectivity occurs. The final command is TRACERT, which displays the path taken by a packet to get to a destination computer.

Upon completion of this lab, you will be able to:

• Use WINIPCFG or IPCONFIG to verify the TCP/IP configuration

• Use PING and TRACERT to troubleshoot the TCP/IP configuration

• Use NSLOOKUP to verify the DNS configuration

Set Up

For this lab, you will need a computer running Windows 98, Windows 2000, or Windows XP.

Exercises

In these exercises you will use the utilities WINIPCFG, IPCONFIG, PING, and TRACERT.

Using WINIPCFG

To use WINIPCFG,

1. Use the following sequence in Windows 98:

   Start Programs MS-DOS Prompt.

2. Type WINIPCFG and press Enter. Select your adapter from the drop-down list.

3. Click the More Info button.

4. Record your IP address, subnet mask, default gateway, and hardware address:

5. Record when the lease was obtained:

   Note

   Lease information will appear only if you are using automatic configuration.

6. Click the Release button. Then click the Renew button.

7. Review the TCP/IP information. Is it the same? Yes No

8. Record the new lease information:

9. Record the new IP address if you received one:

10. Close the IP Configuration window.

Using IPCONFIG

To use IPCONFIG,

1. Follow this sequence in Windows 2000/XP:

   Start Run

2. Type cmd. Press Enter.

3. Type ipconfig /all. Press Enter.

4. Record your IP address, subnet mask, default gateway, and physical address:

5. Record when the lease was obtained:

   Note

   Lease information will appear only if you are using automatic configuration.

6. Type ipconfig /release. Type ipconfig /renew. Press Enter.

7. Review the TCP/IP information. Is it the same? Yes No

8. Record the new lease information:

9. Record the new IP address if you received one:

Using PING

To use PING,

1. Open a command-prompt window.

   In Windows 98:

   Start Programs MS-DOS Prompt

   In Windows 2000/XP:

   Start Run. Type cmd. Press Enter.

2. Type ping 127.0.0.1. Press Enter to ping the loopback address. Doing so verifies whether the TCP/IP protocol stack is working properly.

3. Ping your IP address by typing ping X.X.X.X. Press Enter. Replace the Xs with the IP address that you recorded earlier. Doing so verifies that your network adapter is functioning properly.

4. Ping the IP address of the default gateway to verify that you have connectivity to the router.

5. Ping the IP address of a site on the Internet to verify connectivity outside of your local network.

6. Ping the name of your favorite site on the Internet to verify that DNS is working properly.

   Note

   You may not get a reply from some sites on the Internet. Many sites have disabled responding to pings as the result of the many Internet attacks in the recent years.

Using TRACERT

To use TRACERT,

1. From the command prompt, type tracert X.X.X.X. Press Enter. Replace the Xs with the IP address or name of your favorite site on the Internet.

2. Record the number of hops taken to get to the site:

   Note

   You may not get a reply from some sites on the Internet. Many sites have disabled responding to TRACERT as the result of the many Internet attacks in the recent years.