From Windows, go to:
Start Menu -> Click Run... -> Type in "cmd" and click OK -> When the DOS prompt opens type in "tracert server.ip" replacing server.ip with the IP of the server your site is on.
From Mac, go to:
Open Macintosh HD/Applications/Utilities/Terminal -> Type in "traceroute server.ip" replacing server.ip with the IP of the server your site is on.