Where your mind is is based on your mindset going into the interview. If you're thinking all this when the interviewer asks the questions, you definitely haven't practiced enough, and you didn't spend the time before the interview getting into the right mindset.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.