Yes, you should treat your Registrar as a supplier. You should put them through the same qualifying process you would any critical supplier. When I do certification/surveillance audits, I check to see that the registrar is on the approved supplier list, if not I let them know they should be. Should you audit them, IMHO I would say no. You are already paying enough for some of these registrars services, let them come to you. Should you interview them have them visit you, have them fill out a supplier qualification form yes! If they see it an antagonizing then I would not use them. Yes, it is a delicate relationship, but they are not special. If they screw up call them on it, they would you wouldn’t they. I let our current registrar know in no uncertain terms they are not meeting our expectations, and that I am very unhappy with their current services. Not the auditors they are sending us, but the office staff. Don’t be afraid of your registrar.