Question : Active Directory Replication

I have setup two Windows 2008 Domain controllers one in Missouri and one in New Jersey.  I am trying to get them to replicate over a VPN which is also going through an ISA 2004 firewall.  I have run DCDIAG and it states that it cannot replicate and the firewall is capturing a bunch of RPC errors.  I have a site to site VPN going through the ISA and my question is there something I need to configure on the ISA to allow RPC through

Answer : Active Directory Replication

Have you checked to see whether the firewall is blocking any traffic?