CertiGuide to A+ (A+ 4 Real)  9  Chapter 14: Networks       9  What is a Network?            9  Troubleshooting Network Problems

Troubleshooting Network Cards 1 Troubleshooting DNS and Name Resolution

If you cannot access a resource on the network, the first step is to confirm you actually have a valid IP address. Do this by opening a command prompt and using the IPCONFIG command to display your IP configuration. Look for telltale signs such as an IP address beginning with the APIPA address 169.254.x.x – this is a dead giveaway that your machine cannot retrieve an IP address from a DHCP server. In versions of Windows prior to 2000, a 0.0.0.0 IP address signifies the same problem.

If you have a valid IP address, check that you can communicate with the resource you are trying to access. To do this, use the ping command to ping the target IP address. A timeout may indicate the host is offline²¹⁷, whilst a “Destination host unreachable” message may indicate that a gateway device somewhere between you and your target is inoperable.

First, confirm your default gateway is correct by checking the output of the IPCONFIG command, and by pinging it. Next, use the TRACERT command to locate where your data packets are being lost. At this point, you will have a good idea of where the problem lies, and can proceed to troubleshoot the issue directly.

Troubleshooting Network Cards 1 Troubleshooting DNS and Name Resolution