As everything relies heavily on DNS and the ability to resolve names to IP’s etc., if your DNS upstream is not working or something firewall/internally is not working, things do not always function as they should and you are presented with false positives.
A friend of mine reached out saying he has seen this error and things are not working as they should. The figure below shows the informational alert logged on Exchange.
By doing a few tests, the server for whatever reason could not query DNS (Active Directory) and the DC’s that handle the DNS queries were not resolving anything.
After a reboot of both the domain controllers and Exchange servers, this informational alert went away and stuff was functioning as it should. It is hard to say what caused this but looks like there was a drop or blip somewhere which caused everything to lock up.
Later on it was confirmed that the upstream provider did have issues but always remember to start with basic troubleshooting.
Hope it helps.