Wierd DNS

I am new to this company. I ran some checks areound the network to get the feel of the place, and in doingso found some oddities. When I run netdiag on the (only one in network) domain controller, it fails the DNS test, saying that the DC is not properly registered. I tried ipconfig /registerdns, but that didint seem to fix the problem. I looked in DNS, but it seemed to me like all the records were there. Any ideas as to whats going on? Clients can log ionto the domain, so the DC is functioning….