The most basic diagnostic tool utility to test communications in the wold of networking is Ping.
If you cannot connect to a system, try to ping it's IP asdress using the format
C:\>ping 202.000.000.000.
You can also use the name of the server, for example
C:\>ping www.yahoo.com.
If you're trying to fix your own system and want to ping continuously for testing purposes, use the -t option, for example
C:\>ping -t 202.000.000.000.
Finally, if you want to try to obtain the name of the computer for which you already know the IP address, type ping -a 202.000.000.000, and the name of the system will usually be returned to you.
This is helpful in cases where your firewall logs show a potential hacker's IP, and you want to know which ISP they are using for the purposes of reporting them.
Thanks for reading ... should come in handy