Cannot Add Windows Server 2012 as Member Server to Existing Domain
We get the message "The specified domain either does not exist or could not be contacted."
Check DNS. Rule #1 for all AD problems is "Check DNS." Rule #2 is "If it's not DNS, you're in trouble."
From the command prompt are you able to ping or do an nslookup of the FQDN of your AD domain? I'm betting you just have the 2012 server's DNS list misconfigured in the network adapter properties.
There's no "trick" to making 2012 a member server, troubleshoot this the same way that you would 2003 or 2008.