Troubleshoot connectivity problems on Windows networks, part 1
This article was first published in WindowsNetWorking on August 14, 2008.
Today’s network hardware and software is more reliable than ever but even so, things do occasionally go wrong. In this article series, I am going to discuss some troubleshooting techniques that you can use when a host on your Windows network has trouble communicating with other network hosts. For the sake of those with less experience in working with the TCP/IP protocol, I’m going to start with the basics, and then work toward the more advanced techniques.
Verify Network Connectivity
When one host has trouble communicating with another, the first thing that you must do is to gather some information about the problem. More specifically, you need to document the host’s configuration, find out if the host is having trouble communicating with any other machines on the network, and find out if the problem effects any other hosts.
For example, suppose that a workstation is having trouble communicating with a particular server. That in itself doesn’t really give you a lot to go on. However, if you were to dig a little bit deeper into the problem and found out that the workstation couldn’t communicate with any of the network servers, then you would know to check for a disconnected network cable, a bad switch port, or maybe a network configuration problem.
Likewise, if the workstation were able to communicate with some of the network servers, but not all of them, that too would give you a hint as to where to look for the problem. In that type of situation, you would probably want to check to see what the servers that could not be contacted had in common. Are they all on a common subnet? If so, then a routing problem is probably to blame.
If multiple workstations are having trouble communicating with a specific server, then the problem probably isn’t related to the workstations unless those workstations were recently reconfigured. More than likely, it is the server itself that is malfunctioning.
The point is that by starting out with a few basic tests, you can gain a lot of insight into the problem at hand. The tests that I am about to show you will rarely show you the cause of the problem, but they will help to narrow things down so that you will know where to begin the troubleshooting process.
PING
PING is probably the simplest TCP/IP diagnostic utility ever created, but the information that it can provide you with is invaluable. Simply put, PING tells you whether or not your workstation can communicate with another machine.
The first thing that I recommend doing is opening a Command Prompt window, and then entering the PING command, followed by the IP address of the machine that you are having trouble communicating with. When you do, the machine that you have specified should produce four replies, as shown in Figure A.
Figure A: The specified machine should generate
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