DNS on Windows Server 2003, 3rd Edition

Wrong or Inconsistent Answer

If you get the wrong answer when looking up a local name or you get an inconsistent answer, depending on which name server you ask or when you ask, first check the synchronization between your name servers:

• Are they all holding the same serial number for the zone? Did you forget to increment the serial number on the primary after you made a manual change (see problem 1)? If you did, the name servers may all have the same serial number, but they will answer differently out of their authoritative data.

• Did you forget to restart the primary after making a manual change (see problem 2)? Then the primary returns (via nslookup, for example) a different serial number than the serial number in the zone datafile.

• Are the secondaries having trouble updating from the primary (see problem 4)?

• Is the name server’s round-robin feature rotating the addresses of the domain name you’re looking up?

If you get these results when looking up a name in a remote zone, you should check whether the remote zone’s name servers have lost synchronization. You can use tools like nslookup to determine whether the remote zone’s administrator has forgotten to increment the serial number, for example. If the name servers answer differently from their authoritative data but show the same serial number, the serial number probably wasn’t incremented. If the primary’s serial number is much lower than the secondary’s, the primary’s serial number was probably accidentally reset. We usually assume ...