Hmm.. Well, since you are running a Domain, you have a Domain Controller.
Most Admins will install the DNS server on top of the DC, so that is where
you look first. It will be under Start > Administrative Tools > DNS
Then take a look at your Forward Lookup Zone. All computers that are joined
to a Domain will have a record there indicating the Name and IpAddress where
it can be reached. DNS provides name resolution (to IPAddress) so other
computers can find the one they need to reach.
Actually, I am a little surprised that you are running a Domain without
someone to manage it. Or was this left up to you?
--
FE
Wm P
MVP Microsoft Networking
MCP | CCNA | A+