What exactly do you mean by "user"? Can they query DNS traffic by IP address / subnet? Exactly what are all of the restrictions there?
EDIT: Is there a whitelist of things they can query by or do you simply trust them to be good citizens, have a binding legal agreement, all of the above?
What exactly do you mean by "user"? Can they query DNS traffic by IP address / subnet? Exactly what are all of the restrictions there?
EDIT: Is there a whitelist of things they can query by or do you simply trust them to be good citizens, have a binding legal agreement, all of the above?