Windows:
Click Start
Click Run
type 'cmd.exe' (without quotes)
type 'tracert www.yourdomain.com' (without quotes)
Look at the last or next to last hop (line) and it should say vz##-tx.privatesystems.net
Mac:
Open Applications folder
Open Utilities folder
Open Terminal
type 'traceroute www.yourdomain.com' (without quotes)
Look at the last or next to last hop (line) and it should say vz##-tx.privatesystems.net
-Caleb