I don't believe that information is avalable that way.
Since the user belongs to a group that is enumerated as a group that may
access the SQL Server he is allowed access at a certain level ... that you
could find out. But how that user got it ... I don't think so ... not
without some sort of extended stored procedure ... or command line tool.
How can i find what nt user group sql used for authentication. Exp. user
belongs to nt group Users. Domain\Users have rights to sql and that is how
is gaining access. Is there anyway I can findout for trans-sql that j_doe
belongs to domain\users???? I hope I am explaining the right. What NT group
a user belong to that let them into sql?