NT 4.0 to Win2k Upgrade in place

I am running tests for an upgrade in place for an NT 4.0 domain to Win2k Active Directory. All member servers are already Win2k. I add a BDC to our domain, sync it, pull it to my test and promote it to PDC. SAM and all security caries over fine on upgrade. Problems arise with trying to use existing Win2k server running DNS as the DNS server for the upgraded domain. Other problem is our current domain name is not a fully qualified domain name. When I put FQDN in during upgrade, I run into DNS issues. Anyone have resources I could read on these issues?