This may be a bit difficult question. I am attempting to create a test network that properly resembles production.
2003 functional level
I promoted a server(2008R2) to dc on production, then removed it from the network. Set it up as the only dc on a test network, then seized all FSMO roles. I have no problem authenticating and DNS properly resolves, the issue is attempting to join machines to the domain. ldp.exe shows port 389 is open and can see the domain. The firewall is turned off. Schema is set to version 47(2008R2). IPv6 is enabled.
Any further relevant information just ask.