We have a branch office Server 2008. its active directory was not replicating and eventually went to tombstone. I assume users must have been authenticating over the site to site VPN to a main office DC.
I rtied the registry fix to allow it to synch when out of date, but that did not work.
I eventually ran dcpromo /forceremoval, ran metadata cleanup, killed it out of DNS. I still cannot run dcpromo, or join this to the domain. At one point I changed its name and IP address and still couldnt join.
It currently is a stand alone server. It has a secondary DNS zone for my domain, which works. it has a good connection to the main DC, can ping the domain name and get a response from the main DC. can ping the main DC by name and get a correct response.
On both functions I get to the name and password box, then get network path not found, or forest not available.