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Troubleshooting IP Addressing
Troubleshooting IP addressing is obviously an important skill because running into trouble
somewhere along the way is pretty much a sure thing, and it’s going to happen to you. Because of this nasty fact, it will be great when you
can save the day because you can both figure out (diagnose) the problem and fix it on an IP
network whether you’re at work or at home!
Here are the four troubleshooting steps Cisco recommends:
1. Open a DOS window and ping 127.0.0.1. This is the diagnostic, or loopback, address,
and if you get a successful ping, your IP stack is considered to be initialized. If it fails, then
you have an IP stack failure and need to reinstall TCP/IP on the host.
2. From the DOS window, ping the IP address of the local host. If that’s successful, your network
interface card (NIC) is functioning. If it fails, there is a problem with the NIC. Success
here doesn’t mean that a cable is plugged into the NIC, only that the IP protocol stack
on the host can communicate to the NIC (via the LAN driver).
3. From the DOS window, ping the default gateway (router). If the ping works, it means that the
NIC is plugged into the network and can communicate on the local network. If it fails, you
have a local physical network problem that could be anywhere from the NIC to the router.
4. If steps 1 through 3 were successful, try to ping the remote server. If that works, then you
know that you have IP communication between the local host and the remote server. You
also know that the remote physical network is working.
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