Here's a quick way to find find out the server name of the AD domain controller on your network.
c:\> nltest /dc:labs.example.org
If you are running on a Linux machine, you also can find out the server name and IP address in AD too.
$ nslookup -type=all _ldap._tcp.dc._msdcs.labs.example.org
$ dig @dns1.example.org _ldap._tcp.dc._msdcs.labs.example.org -t srv
$ dig @dns1.example.org _ldap._tcp.dc._msdcs.labs.example.org -t any