adding domain users as users on local machine

Ever tried to add domain users as users on a local computer? I did and ran across something funny. The local computer was the only pool available to draw from. The PC was a member of the domain and could see the domain controller. Finally I added a reference to the DC in the hosts file. It resolved the issue. It was a DNS problem that I'll resolve later. I didn't see this listed anywhere for free on google so I thought I'd list it here just in case someone else ran against it.