How to get the groups of a user in Active Directory?

Question

I use from this code:

   List<GroupPrincipal> result = new List<GroupPrincipal>();

   // establish domain context
   PrincipalContext MyDomain = new PrincipalContext(ContextType.Domain);

   // find your user
   UserPrincipal user = UserPrincipal.FindByIdentity(MyDomain , username);

   // if found - grab its groups
   if(user != null)
   {
      PrincipalSearchResult<Principal> groups = user.GetAuthorizationGroups();

      // iterate over all groups
      foreach(Principal p in groups)
      {
         // make sure to add only group principals
         if(p is GroupPrincipal)
         {
             result.Add(p);
         }
      }
   }

but on this line ( user.GetAuthorizationGroups() ) I got an exception

This server is not operational

Answer 1

In a web environment:

System.Web.HttpContext.Current.Request.LogonUserIdentity.Groups

or in your context:

user.GetGroups()

MSDN

Answer 2

From what I remember, the exception can be caused by the fact that the domain name cannot be resolved with any available DNS. Make sure that it is and the exception goes away.