Windows 2000 DNS includes a caching resolver, which enables negative caching by default. In some cases, a user might not be able to access a system, shared resource, or Web page because Win2K added the negative (i.e., unsuccessful) DNS lookup to its negative caching. To prevent such a problem, you can disable negative caching.
Start regedit and go to the HKEY_LOCAL_MACHINES\SYSTEM\CurrentControlSet\Services\DNSCache\Parameters registry subkey. Set the value of NegativeCacheTime to 0 (the default value is 300 seconds).