DNS on Windows Server 2003, 3rd Edition

Caching

The Windows 2000, Windows XP, and Windows Server 2003 resolvers store every record they receive in a shared cache available to all programs on the system. The Windows NT 4.0 resolver caches, but only on a per-process basis. For example, if you have two different web browsers running (say, Internet Explorer and Netscape Navigator), each has its own copy of the resolver with a separate cache. Windows 98, 95, and 3.1 resolvers don’t do any caching.

The Windows 2000, Windows XP, and Windows Server 2003 resolvers obey the TTL (time to live) field on resource records they cache, up to a maximum of 24 hours by default. So if a record specifies a TTL longer than that, the resolver rounds down to 24 hours. This maximum TTL is configurable with a Registry setting:

MaxCacheTtl
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNSCache\Parameters
Data type: REG_DWORD
Default value: 86,400 seconds (= 24 hours)

(On Windows 2000, this Registry value is called MaxCacheEntryTtlLimit.)

The Windows 2000 and Windows Server 2003 resolvers also support negative caching. Windows Server 2003 caches negative responses for fifteen minutes by default, while Windows 2000 caches them for only five. This negative caching timeout is also configurable with a Registry setting:

MaxNegativeCacheTtl
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNSCache\Parameters
Data type: REG_DWORD
Default value: 900 seconds (= 15 minutes)

(On Windows 2000, this Registry value is called NegativeCacheTime.) To disable ...