You don't want to ask the actual question about the specific application, because it gives a strong advantage to a candidate who has worked on that very specifi

You don't want to ask the actual question about the specific application, because it gives a strong advantage to a candidate who has worked on that very specific situation in the past (and they may be able to sneak through just by regurgitating from memory.) It's better to have a scenario they're unlikely to have seen previously. As an interviewer, I'm not interested in your ability to remember solutions you received from others, I want to know how you deal with a problem you haven't seen before. Sometimes folks call these "puzzlers" but I think they're unfairly lumped in with true "puzzlers" - crap like "why is a manhole round" where there's a right answer that depends on either experience or some specific insight. A question where you're asking a candidate to walk through their thought process on a hypothetical (but reasonable) situation isn't "puzzling" unless you just can't handle the question.