I ask a question of Mike. This form is correct, but you seldom hear it. You might see it more in written English. I ask a question toward Mike. You will never hear this form. It is technically correct, I suppose, but sounds very awkward. There is one situation where you would use 'toward', however. If you were talking with several people with Mike being one of them, if you wanted to emphasize that you were asking a question just of Mike, you would say "I directed a question toward Mike." 'Directed' is necessary here.

neither! :) 最好是 "ask Mike a question"! this is the most common way to say it. ”ask a question of" 也行! 但比較正式的，我從來沒用過 ！