We have 3 DCs in one site in one subnet. 1 Physical, 2 Virtual.
Right now, one of the virtuals is playing host to all of the FMSO Roles (moving soon, but I want to nail down this issue first.) I did a reboot on the this DC and all of the other DCs stopped serving AD requests.
Errors like the following started showing up:
Event 2138: The processing of Group Policy failed because of lack of network connectivity to a domain controller. This may be a transient condition. A success message would be generated once
the machine gets connected to the domain controller and Group Policy has succesfully processed. If you do not see a success message for several hours, then contact your administrator.
Event 14550:The DFS Namespace service could not initialize cross forest trust information on this domain controller, but it will periodically retry the operation. The return code is in the record data.
Event 510:Folder redirection policy application has been delayed until the next logon because the group policy logon optimization is in effect.
Even my Exchange server went offline complaining that DC was not available.
Event 2155: Process ExSetupUI.exe (PID=4764). Exchange Active Directory Provider received a request to connection to domain controller DC2.alllanguages.com but that domain controller is not available. Use the
Ping or PathPing command-line tools to test network connectivity to local domain controllers. Run the Dcdiag command line tool to test domain controller health.
When I do a DCDiag, the only errors I get are from the event log about printer drivers from rdc sessions.
I suspect DNS issues, but am running out of things to look at. Anyone have any suggestions to look for?