Verifying IP Installation

After you have configured TCP/IP, you can use two command-line tools, IPConfig and Ping, to test the configuration and connections to other TCP/IP hosts and networks. This type of testing ensures that TCP/IP is functioning properly.

Note 

In TCP/IP terms, a host is defined as any computer on the network, regardless of its operating system or its role as client or server, that is not forwarding packets between subnets.

Using IPConfig

Use the IPConfig tool to verify the TCP/IP configuration parameters on a host. This helps to determine whether the configuration is initialized, or whether a duplicate IP address exists. Use the ipconfig command with the /all parameter to verify configuration information.

Tip 

At the command prompt, type ipconfig /all|more to prevent the ipconfig output from scrolling off the screen; to scroll down and view additional output, press the Spacebar.

The result of the ipconfig /all command is as follows:

• If a configuration has initialized, the IP address and subnet mask appear, and, if assigned, the default gateway for each TCP/IP interface also appears. When appropriate, IPConfig also displays the host name, the primary DNS suffix, the DNS suffix search list, the media access control (MAC) address, the IP address of each DNS server, the IP address of each WINS server, and the IP address of the DHCP server.

• If TCP/IP is configured with a static IP address and a duplicate IP address exists, the IP address appears; however, the subnet mask is 0.0.0.0.

• If the computer is configured for automatic addressing and APIPA, and cannot obtain an IP address from a DHCP server on the network, the IPConfig tool displays the IP address as the address provided by APIPA. This is an address in the range of 169.254.0.1 to 169.254.255.254. APIPA also configures the subnet mask of 255.255.0.0.

Using Ping

After you have verified the TCP/IP configuration, use the Ping tool to test connectivity. Ping is a diagnostic tool that you can use to test TCP/IP configurations and diagnose connection failures. Use the Ping tool to determine whether a particular TCP/IP host is available and functional. To test connectivity, use the ping command with the following syntax:

ping hostname 

As an example of the results you receive using the Ping tool, if you were to successfully ping 172.31.23.17, you might receive the following response:

========================================================================
Pinging 171.31.23.17 with 32 bytes of data:
 
Reply from  172.31.23.17: bytes=32 time<1ms TTL=128
Reply from  172.31.23.17: bytes=32 time<1ms TTL=128
Reply from  172.31.23.17: bytes=32 time<1ms TTL=128
Reply from  172.31.23.17: bytes=32 time<1ms TTL=128
 
Ping Statistics for 172.31.23.17:
       Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 0ms, Average = 0ms
========================================================================

Using IPConfig and Ping

The following steps verify a computer s network configuration and test router connections:

1. Use the ipconfig command to verify that the TCP/IP configuration is initialized.

2. Use the ping command with the IP address of the default gateway to verify that the default gateway is operational and that your computer can communicate with the local network.

3. Use the ping command with the IP address of a remote host to verify that the computer can communicate through a router.

The Network Diagnostics feature of Windows XP Professional provides network and connectivity testing and validation. Test results can be viewed in a command window or by using a browser. The Network Diagnostics feature can effectively replace the command-line processes used for IPConfig and Ping.

For more information about using the ping command, see Testing the Network Connection with Ping and PathPing later in this chapter.

Note 

Many hosts on the Internet discard the ICMP traffic of the Ping command and do not reply to ping messages. If pinging to one remote host does not work, try several different ones.