dumb question

a statement made before asking a questions of which one is supposed to be really familiar with the answer

Fred: Mike, 'Dumb question', how do you display a full screen of a power point presentation
Mike: Dude, press F5.

Dumb-ass question

A question that has no point or is no ones concern

" Boy: hey are you dating (insert race)

Girl: that's a dumb-ass question, why do you care"
"do you want to get drunk tonight?"