When attempting to make a Windows 2000 server a secondary zone of an NT 4.0 DNS server, you must input the primary...
suffix of the DNS zone in order for the zone to transfer.
If your NT 4.0 DNS zone is my.company.com, you must enter this is the DNS information tab on the Windows 2000 server. The zone transfer cannot complete unless this information is provided. You will only get a transfer of the primary zone, but no other zone information such as reverse lookup zones.