- The Server is off (the most obvious one)
- The Switch is off(also common issue)
- The Server tried to boot of other media (Flash drive/CD Rom/USB Drive) and didn't boot correctly.
- The network card didn't reconnect to the switch(not very common)
- The Server/PC was set to DHCP networking and now has a new IP after power was restored.
- The Server/PC was set to DHCP and the DHCP server didn't come back up, so the server doesn't have an IP
Check the following to try and resolve:
- Check that you can ping the IP of the server.
- Check that there is something on the screen of the server. You must be able to type on the screen or use the mouse.
- If the Server is off, switch it back on.
- If you Can you login to the server, check if the network settings is still correct and make sure you can ping something on the network.
- unplug and then reconnect the networking cables if everything above is correct.