You can find out what server you are on using two different ways, each one revealing which server you are on.
Method 1: Welcome Letter
If you stored your welcome letter, you will find the server that you are on. If you do not have the welcome letter, login to the Client Area and look at all e-mail that has been sent to you, which your welcome letter should appear.
Method 2: A Trace Route
You can do a trace route to your main IP address or any active IP address hosted on your service. Usually, the hop before reaching your VPS is the server you are on. We create a PTR (reverse DNS entry) for all of our nodes, so it is easy to identity which server you are on.