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