We have a domain controller (exchange box) hosted at our hosting provider. We need to set up a local domain controller so we do a VPN and local authentication tasks.

I can make the PDC accept all connections from our Office IP. How do I get the office router to correctly allow two way communications between the PDC (cloud) and the local DC. Is there a list of ports I need to pass through to the local DC?

Thanks!

"PDC" and "BDC" used for clarity--I know that the concept is obsolete.