Hope this analogy will help you get out of the dark.

"a562.cd.akamai.net" is a description of how to get to one or more IP-numbers (Rome).
"www.microsoft.com" is another description to get to the same IP-number(s) (Still Rome).

You're asking, given "Rome", to be able to tell all the possible ways to Rome. There could be one, there could be thousands. You won't be able to find out from "Rome". There is no way to know, unless you start trying them out one by one (in a Shakespeare monkey manner).

Another analogy. You call yourself "marknm". But can you know what other people call you unless they tell you? No. Not unless your psychic. And even that could be considered them telling you what they call you.

Hope this clears things up.

Liz