Bryan J. Smith wrote:
Windows NT5+ (2000+) client systems have a _flawed_, _default_ logic to "hold down" DNS resolution upon failure. That
means if a DNS resolution fails, Windows clients will
_not_ requery the server _until_ that timeout passes. There is a registry hack to change this as follows: [ From
http://www.winguides.com/registry/display.php/1203/ ]
'To change the DNS cache timeout for negative responses (where a lookup failed). Windows 2000 - Create or modify the DWORD value called "NegativeCacheTime". Windows XP and .NET Server 2003 - Create or modify the DWORD value called "MaxNegativeCacheTtl". Set the value to equal the required timeout in seconds the default is 300 (5 minutes). Restart Windows for the changes to take effect.'
It's my #1 recommendation until you resolve the problem. UNIX clients/resolvers _never_ (AFAIK) cache a "failure," only Windows -- which I think is flawed, but there is a reason for it (that has to do with legacy SMB file/print).
Regardless of what solution you come to on the server, consider doing the above.
Just to add to your knowledge base:
On Windows system, you can manually flush its dns cache, failed and otherwise, by opening a Command Window and typing:
ipconfig /flushdns