I have a small environment with 3 sites connected by a single site link.
Site 1 has two Domain Controllers
Site 2 has 1 Domain Controller
Site 3 has 1 Domain Controller
All DCs are 2008 R2. DFL and FFL are 2008R2. All DCs are GCs and DNS Servers.
What I'm seeing is two warning events and 1 error event every 15 minutes on one of the Domain Controllers at Site 1 - but not on ANY of the other Domain Controllers - including the secondary DC also at Site 1.
Here's what I'm seeing:
Event ID: 1865 -- The KCC was unable to form a complete spanning tree network topology...
Event ID: 1566 -- All directory servers in the following site that can replicate the directory partition over this transport are currently unavailable. (site information is shown and points toSite 3)
Event ID: 1311 -- The KCC has detected problems with the following directory partition. CN=Configuration,DC=mydomain,DC=local
There is insufficient site connectivity information for the KCC to create a spanning tree topology or one or more directory servers with this directory partition are unable to replicate...
I have run dcdiag /test:connectivity on All DCs with no issues. Again, only ONE of the two DCs at Site 1 are seeing these errors, ALL OTHER DCs are fine.
I have also followed the steps here: http://social.technet.microsoft.com/wiki/contents/articles/1375.event-id-1311-microsoft-windows-activedirectory-domainservice.aspx to verify my settings in AD Sites and Services
Why would only one of my DCs at this site experience this issue? What can I do to resolve this problem?