I have a domain with two dc's. I have been using RDC to access one from the other, that is until this morning. Now, I get the error msg that "the target computer is not accessible because it is either 1) turned off or 2) RDC is turned off or 3) the computer is not on the network." None of this is true. After research I found that I could connect using the target machine's IP. But when I ping it the DNS resolution is to the network's public IP and it fails. I checked th e DNS service on both DC's. On the target machine it's working, but on the other DC, it has failed to start with an error code 4000, "The DNS server was unable to open Active Directory. This DNS server is configured to obtain and use information from the directory for this zone and is unable to load the zone without it. Check that the Active Directory is functioning properly and reload the zone. The event data is the error code." What to do next? How does one re-load a zone and how could this have suddenly stopped working?