There are no dumb questions.
When I was in collage, one professor liked that saying, and when someone askeda question that might at first seem obvious, he would reply with the commone,"That's what I call a dumb question- and they are the best kind" and then explain why the question wasn't dumb and plumb the depth behind the "simple" question.
I got what he meant. But there was one student who twice asked "dumb questions" and later took the prof to task for singleing her out.
As someone who has moderated forums for years now, I always welcome the "dumb" question. Because if one person is thinking it, so is somebody else. We're all new at one time or another.