It aint that difficult. Put your pc in Internet Connection Sharing and run Wireshark or something on your pc. You will be able to sniff the ip your ps3 connects to. You can also use this technique to download some psn trailers or even demo's on your pc.
[QUOTE="PaulMartin1967, post: 0]I need to find out for some IT guys at University what address does the PS3 connect to when trying to go online? Anyone know?[/quote]
Why does the IT guy care?
I assume you're trying to setup your PS3 in your dorm room or something of the like - Correct?
They may require you to register your MAC address for access. If so, the easiest thing to do is really hide everything behind a router and that's what you register (it will use DHCP to get an IP address, DNS servers, etc. - It will then act as the server for your equipment on a subnet - i.e. when your PC and PS3 try to do DHCP access it will get it's IP address assigned from your router on the subnet you created, but still get the DNS Server info that the router was given when it connected.)
Unless they're blocking you from getting outside of their network, there's no reason for them to care what the address is that the PS3 is trying to connect to when connecting to PSN. I'd actually assume it's multiple addresses (one for logging on to main PSN server, others being used for downloading game content.)