This error message is appearing repeatedly in the DNS Event log:
The DNS server was unable to open zone _msdcs.NATIONAL.local in the Active Directory from the application directory partition ForestDnsZones.NATIONAL.local. 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 do I need to do to resolve this issue.