AD Replication - SOmetimes getting "RPC server is unavailable" error
Posted on 2012-08-19
I have 2 Windows 2008 DCs in 2 different locations and I am often getting Replication errors from the AD replication, usually the typical "RPC server is unavailable".
I know this is easy to troubleshoot when it NEVER works, but here like 90% of the time it works and then again i sometimes have a situation where it can't replicate for a few minutes up to an hour. The weird thing is that even though I am getting the AD replication errors (RPC unavailable) i can PING, access shares, open RPD sessions and such between the 2 servers, so it's not like connectivity on that route is down or so. I'd also rule out the typical suggestions (Firewall blocks something, DNS problem, time synchronization) as it works like 90% of the time just fine. Any ideas what else i could try?
Neither DCDIAG nor REPADMIN have given any useful information. When the error occurs i can see the "RPC server not available" messages in REPADMIN but what puzzles me is that if the RPC service is really "dead" then i also shouldn't be able to get onto that machine via RPD or CIFS, but that always works fine, it's really just the AD replication that is having issues. DFS replication is also working fine, files in the DC SYSVOL get replicated instantly.
Any ideas or comments welcome!