Puzzles are fun, but really not the way to judge a person. If I were interviewing for a person and wanted to test for technical know how, I'd just ask them how

Puzzles are fun, but really not the way to judge a person. If I were interviewing for a person and wanted to test for technical know how, I'd just ask them how they think ___ works (where the blank is some popular, semi-related product), and use that as a spring board to talk with them for the next hour about stuff. You get a good sense for the type of knowledge and comfort people have for material that's actually relevant to the job at hand, and on top of that you can suss out things like how well you'd work with them.