New Active Directory Site for remote office, or stick to just one site?

New Active Directory Site for remote office, or keep in same site/domain? Scenario:

• Physical (main) Site 1 – West coast
  • Two AD servers (Windows 2008 R2 Standard)
    • Domain.com
    • 192.168.100.x/24
    • fiber internet connection
      
• Physical (branch office) Site 2 – East coast
  • One AD server (Windows 2008 R2 Standard)
    • East.Domain.com
    • 192.168.200.x/24
    • comcast internet connection
      

*The following references to “sites” are not AD “Sites”, just referencing physical locations only.

Site 1’s DNS servers are replicating to each other. There is a persistent VPN tunnel (2 Cisco ASA 5510’s) connecting the West coast with the East coast. The East coast server was not joined to the Domain.com domain (for whatever reason). Instead a sub-domain was created (east.domain.com) and its FQDN is server.east.domain.com.

We are wondering if it would be better to demote the server on the East coast and simply join it to domain.com, because with the way it is set up now, there is no “domain.com” DNS zone on the East coast’s DNS server – only east.domain.com.

Also, what would be the correct IP addresses to have on each DNS server’s FORWARDER tab? In the past I have always put the ISP’s IP address (or any public DNS server like 4.2.2.2 or 8.8.8.8 – anything but another “internal” IP). At Site 1 both DNS servers are set up with OpenDNS, but on Site 2, its Forwarders are pointing to the two internal IP addresses of the AD servers at Site 1. I changed Site 2’s Forwarders to OpenDNS, and suddenly no one at Site 2 (the branch location) could access resources at Site 1 by DNS name (i.e. Http://servername). Does this mean “Active Directory Sites and Services” is set up incorrectly? Because there is no domain.com Forward Lookup Zone in DNS at Site 2 with Site 1’s DNS records, I was afraid this would happen. I am not too familiar with AD Sites and Services, but in DNS on Site 2, shouldn’t domain.com be a child node within east.domain.com?

All of the resources that this company uses are located at Site 1. Site 2 is simply a branch office with one server and a printer, with a bunch of users who constantly access resources at Site 1 via VPN. There may be a time however, that Site 2 will be just as large as Site 1, so I’m thinking it would be better to get “AD Sites and Services” running properly rather than demoting/dcpromo’ing Site 2’s AD server into domain.com.