:TCP/IP on Windows

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TCP/IP on Windows

When troubleshooting TCP/IP, start close to home and work outward. Make sure the problem machine is funcitoning properly, test the network in general, and then check the Interenet connection.

Start pinging

In a typical network, you have this order (client->gateway->server) or (client->gateway->internet). First, attempt to ping yourself from the Windows command prompt. Your local loopback address for such testing is Your users should see a response.

If you do not receive a successful ping from the machine's loopback adapter, it's likely that the machine's TCP/IP stack is not working. Try re-installing the TCP/IP protocol from the Network Control Panel.

In previous verisons of Windows, rebuilding the TCP/IP protocol stack was a simple operation--you just removed and reinstalled TCP/IP. In Windows XP, you can't just remove TCP/IP because it's considered an integral part of the operating system.
However, XP does come with a command-line utilityed--called NetShell-- that allows you to reset all TCP/IP-related registry settings to their default values. The end result is essentially the same as installing a brand-new TCP/IP configuration. To reset all TCP/IP-related resitry settings, open a command prompt and type the following command:

netsh int ip serset<filename>

You must specify a log file in the <filename> placeholder for this command to work. Details about which registry keys were modified will appear in the log file.

If pinging your loopback worked fine, try pinging sommeone who is on the same subnet as the problem machine

For example, if the IP address is set to, you should ping Be sure the target IP address being pinged is a valid IP address assigned to a system; otherwise you'll receive errors. To determine a machine's subnet, use Winipcfg on Windows 95/98 machines and ipconfig on Windows NT/2000/XP machines.

If you can ping someone on your local subnet, move on to the next step

If you can't you're probably experiences a physical layer failure. The usual suspects are bad cables or a bad NIC. Try replacing the network card and using a new patch cable.

Check the gateway

Get the address of the machine's gateway by using Winipcfg on teh Windows 9x machines or ipconfig on Windows NT/2000/XP. If you don't have a gateay configured, then one will not show up in Winipcfg or ipconfig. Locate the Internet Protocol (TCP/IP) Properties window and ensure that the proper default gateway address is entered or that the machine is confugred to obtain an IP address automatically.

Ping this address; this will prove a solid connection form your PC to the gateway

If you have made it this far, the PC is working, the cabling is working, and the router (gateway) interface is working. You can skip to the next step.
If you receive no response from the gateway and you have one configured, your router is probably configured imporoperly. It must have a local interface (IP Address) on yoru subnet to listen to the traffic on your network. Check to ensure that there is one, and add one if there isn't. If it has one but has sopped working, it could mean you're experiencing a router failure, and others will be affected as well. Converstly the router may be using an old config; check to make sure this isn't the case.

The final step is through the gateway. Ping something that is on the other side of the gateway

In an intranet, ping a printer on a remote subnet. On the Internet, ping Yahoo! ( If you do so successfully, you should not have a problem. If you can't get to a particular system in your network or on the Internet, that resource may not be available.