Basic TCP/IP Troubleshooting

In this document:
Step 1: Verifying that TCP/IP is installed
Step 2: Verifying TCP/IP is shown in the list of protocols
Step 3: Verifying the PC sees connectivity information correctly
Step 4: Verifying network functionality
Other related support information
This document provides steps for proving basic TCP/IP functionality for a network Interface card (NIC).
Step 1: Verifying that TCP/IP is installed

From Windows, click Start, Run, and enter command in the Open field.
At the command prompt, enter the following: PING 127.0.0.1
This command is referred to as the Ping Command or Loopback Address. It is a reserved address and is used just for TCP/IP troubleshooting.
Getting the following (or similar) response proves that the Network card is functioning properly with the other hardware components and that the problem is probably related to settings or line conditions:
Pinging 127.0.0.1 with 32 bytes of data:
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Ping statistics for 127.0.0.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = oms, Average = 0ms

Type exit at the command line to close the window.

Step 2: Verifying TCP/IP is shown in the list of protocols
If the response generated to the ping or Loopback address is different than the one shown in the Verify TCP/IP Installation section above, verify that TCP/IP has been installed and is bound to the adapter. Use the steps below, depending on your version of Windows, to verify that the network hardware is bound to the protocol:
Checking Bindings in XP

Click Start, Control Panel, and click Network and Internet connections.
Click network connections.
Right-click the name of the LAN connection and select Properties.
You should see the name of the network hardware in the Connect using field with Internet Protocol(TCP/IP) selected and listed in the window below.
If Internet Protocol is not selected or is does not appear, then click the Install button to add Internet Protocol.
Click OK when done.


Checking Bindings in 98, Me

From the Windows desktop, right-click Network Neighborhood or My Network Places.
Click Properties from the shortcut menu.
The Network window will be displayed. In the list of network components, highlight the component being used to access the network (for example, name of card or dial-up adapter).
Select Properties and click Bindings. The network card Properties window appears. Verify that TCP/IP -> NAME OF CARD is shown and selected in the list of protocols. The binding to a specific network card may not appear if you have only one network card and are not using a dial-up adapter.


Step 3: Verifying the PC sees connectivity information correctly
Perform the following steps to verify:

From Windows, click Start, Run, and enter command in the Open field.
At the command prompt, enter the following: ipconfig
The last three numbers of the IP address should not end with zero.
The subnet mask usually starts with 255. If this is all zeros, then something is wrong.
The default gateway should also consist of four numbers. If this field is all zeros, something is probably wrong with the connection or settings. If you have four non-zero numbers, write them down and continue to the next step.

Step 4: Verifying network functionality
Next, ping the workstation that you are working from. Although this has already been done earlier by using a loopback address of 127.0.0.1, this only verified that TCP/IP was functional, not the configuration.
Ping for a response from the IP address that is listed as the default gateway. If the default gateway responds, ping more systems on the same segment. Testing communication to other devices on the local segment verifies that communication exists with devices other than the default gateway and confirms that the subnet mask is the same for all of the devices.
If a response was received from every ping thus far, ping a device outside of the router that is providing the default gateway. This confirms the correct default gateway is in use and that it knows how to find the address.
Successful completion of all steps verifies the network card or modem is functioning.
Type exit at the command line to close the window.

Other related support information
Microsoft support article, How to Troubleshoot Basic TCP/IP Problems (in English).
Microsoft support article, How to Reset Internet Protocol (TCP/IP) in Windows XP (in English). Resetting TCP/IP can be a fast way to prevent errors like: Page Cannot Be Displayed.