You can check if your server is online by going to start -> run -> cmd
then type /Ping (realm-ip). If it says host is unreachable, it means your ping was forcefully rejected therefore the server is up. If the server is down then it will time out.
For Example:
(A server thats offline would show) - Using Karazhan server
Ping karazhan.game-host.org (86.82.46.176)
Pinging karazhan.game-host.org [86.82.46.176] with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Ping statistics for 86.82.46.176:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
(A server thats online would show) - Using Mangos GM Server
Ping 5.166.33.37
Pinging 5.166.33.37 with 32 bytes of data:
Destination host unreachable.
Destination host unreachable.
Destination host unreachable.
Destination host unreachable.
Ping statistics for 5.166.33.37:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),.
This can also be used to check multiple servers by createing a .bat file. Simply open up a text file. Next Format the file like so.
/ping xxx
/ping xxx
/ping xxx
then rename the text file and run it in command prompt.
I hope you found this useful.