NTDSUTIL and Operation Master roles questions (or what port is DC stuff replicated over)

I know how to find what Domain Controller's have roles using the GUI tools in windows, now I'm trying to make sure I can do it from the command line. Below is what I'm trying but its not working -- I believe I'm missing a port number.. but what is the default port number?

PS C:\Users\Administrator> ntdsutil
C:\Windows\system32\ntdsutil.exe: roles
fsmo maintenance: connections
server connections: mydc.fqdn.dom
Error parsing Input - Invalid Syntax.
server connections:

I'm pretty sure the syntax is supposed to be

PS C:\Users\Administrator> ntdsutil
C:\Windows\system32\ntdsutil.exe: roles
fsmo maintenance: connections
server connections: mydc.fqdn.dom:port