I had an interesting question through my blog today. An IT Pro had a problem with a server he joined to the domain. The problem was that it just didnt seem to be working properly despite joining the domain fine. He couldnt seem to be able to query Active Directory properly or authenticate domain users. Local accounts worked fine.
Ive seen this one many times. Usually there will be other issues like the Active Directory Users and Computers MMC snapin taking ages to load up. It always points to network configuration and generally its where the member server that youve joined is pointing to an external DNS rather than your Active Directory one. In this case that was the issue. Once he correctly did this everything worked fine and usually it requires an ipconfig /registerdns command to get the correct records into the DNS also for that machine.
Its also a common issue with Exchange servers. Lots of IT Pros configure their Exchange Servers to point at an external DNS (through Windows networking rather than within Exchange itself) which creates huge problems as Exchange leverages DNS for Active Directory heavily. A another approach is to point your Exchange Server at the Active Directory DNS Server and then have that forward requests to an external DNS from there.