A lot of the time I find "spot the bug" questions to be more informative, especially for junior roles. We stopped asking fizz-buzz - just about everyone has heard of it by now and it's pretty easy to just rote learn a solution. Instead we give them the spec for fizz-buzz and a deliberately broken implementation and ask them to fix it. If they get flustered, just asking "what does this program output" usually give a pretty clear indication if they can reason about code in a systematic way.