[InclinedPlane]

I find it's best to ask easy questions (like fizzbuzz) and very hard questions. For easy questions you gauge fundamental competence, those should be things that decent devs can solve as fast as they can write, it makes it easy to weed out the folks who are clueless and somehow have trumped up resumes. For hard questions you go in with the expectation that you're not going to get a solution to the problem, so you concentrate on observing the process the candidate uses, their problem solving skills, communication, the sort of problems they're comfortable with tackling, and so on.