Authentication Services has a negcache which is supposed to keep vasd from going to AD however when a GC can't be found, it was not being used. Bug #489836 was entered to resolve this issue.
Defect ID: 489836 entered/fixed.
vasd: If a GC cannot be reached to resolve an unknown user/group still make a negcache entry for that user/group. This should reduce AD/DNS traffic in DMZ situations where a GC is not available.