DNS on Windows Server 2003, 3rd Edition

Lookups Take a Long Time

Long name resolution periods are usually due to one of two problems:

• Connectivity loss (see problem 7), which you can diagnose with tools like ping and tracert

• Incorrect delegation information (see problem 9), which points to the wrong name servers or the wrong IP addresses

Usually, sending a few pings points to one or the other of these causes. Either you can’t reach the name servers at all, or you can reach the hosts but the name servers aren’t responding.

Sometimes, though, the results are inconclusive. For example, the parent name servers may delegate to a set of name servers that don’t respond to pings or queries, but connectivity to the remote network seems all right (a tracert, for example, gets you to the remote network’s “doorstep”—the last router between you and the host). Is the delegation information so badly out of date that the name servers have long since moved to other addresses? Are the hosts simply down? Or is there really a remote network problem? Usually, finding out requires a call or a message to the administrator of the remote zone. (And remember, whois gives you phone numbers!)

That’s about all we can think of to cover. It’s certainly a less than comprehensive list, but we hope it’ll help you solve the more common problems you encounter with DNS and give you ideas about how to approach the rest. Boy, if we’d only had a troubleshooting guide when we started!