谷哥找到的一段参考：
　　Using the Registry to Control the Caching Time
　　The length of time for which a positive or negative response is cached depends on the values of entries in the following registry key:
　　HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesDNSCacheParameters
　　The TTL for positive responses is the lesser of the following values:
　　The number of seconds specified in the query response the resolver received
　　The value of the MaxCacheTtl registry setting.
　　Notes
　　The default TTL for positive responses is 86，400 seconds (1 day).
　　The TTL for negative responses is the number of seconds specified in the MaxNegativeCacheTtl registry setting.
　　The default TTL for negative responses is 900 seconds (15 minutes).
　　If you do not want negative responses to be cached， set the MaxNegativeCacheTtl registry setting to 0.
　　To set the caching time on a client computer:
　　Start Registry Editor (Regedit.exe).
　　Locate and then click the following key in the registry:
　　HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesDnscacheParameters
　　On the Edit menu， point to New ， click DWORD Value， and then add the following registry values: Value name: MaxCacheTtl
　　Data type: REG_DWORD Default value: 86400 seconds Value data: If you lower the Maximum TTL value in the client's DNS cache to 1 second， this gives the appearance that the client-side DNS cache has been disabled.
　　Value name: MaxNegativeCacheTtl
　　Data type: REG_DWORD Default: 900 seconds Value data: Set the value to 0 if you do not want negative responses to be cached.
　　Type the value that you want to use， and then click OK.
　　Quit Registry Editor.