10.10. Troubleshooting Network Connectivity Problems
You want to troubleshoot network connectivity problems. This is often necessary if a client is experiencing slow logins or network-based failures when accessing resources.
First, make sure your network adapter is working. Generally there should be a flashing green light to indicate the adapter is connected and transmitting data.
After you've checked the hardware, you can run several command-line tools to aid in troubleshooting connectivity issues. A good first step is to ping the target host, which can tell you if the remote host is reachable and how long it takes to reach it:
Here are some of the status messages you can receive from ping:
The host was reachable.
- Request timed out
The target host either did not respond or there is no host configured with the corresponding IP address. You may also see this message if there is a lot of network latency between the two endpoints. You can work around this by using the
-woption with ping and specifying the number of milliseconds to wait for each reply.
- Unknown host
If you used a DNS name in the ping command, this indicates that the DNS name was not resolvable by the DNS client.
- Destination unreachable
The ICMP traffic could not reach the network of the target host. This is often due to a routing problem on an intermediate router or a router being down.
If you've pinged a host and the request timed out or the host was unreachable, a good tool to try ...