Comment by SideburnsOfDoom

> Either understand why the first thing that popped into your head doesn't work without having them tell you why that's the case

I actually like that phrasing. Some thing simple and open-ended, like

"Well, the first thing that comes to my mind is sshd."

And let them talk.

It's generally a true statement, in that it is the first thing that comes to mind, with all the naivete that this implies. And IMHO doesn't unduly pressure the person who has worked with the problem longer.