The caching daemon maintains a cache of users and groups that could not be found when searching the directory. This cache is referred to as the negative cache. Once an item is in the negative cache no further attempts will be made to find the user/group in the directory until the negative cache entry has expired. The default negative cache lifetime is very short (10 seconds), but it can be increased to suit environmental needs. If entries need to be removed from the negative cache before their lifetime has expired, the contents of this cache can be cleared by running vastool flush negcache.