And you may not really expect an answer or want/need an answer. Not quite rhetorical. For example you may be talking about something that happened and wondering who did it and everyone knows who did it including yourself but you ask, 'I wonder who that was.'
A question where one does not want or need anyone to supply an answer is a rhetorical question.
The rhetorical device is either for the question to make its own point, because the question is left hanging for its hearers to consider, or to provide a pretext for its asker to answer it and make his point with that statement.
The rhetorical question is usually defined as any question asked for a purpose other than to obtain the information the question asks.
Gideon O. Burton, Silva Rhetoricae, Brigham Young University. Rhetorical questions
It depends upon your motive for asking...
Perhaps Machiavellian - practising, or characterised by, (esp. political) expediency in preference to morality; unscrupulous, duplicitous; astute, cunning, scheming (OED).
One who is doing this is probably testing the water; perhaps they are just itching to name you-know-who (as an example) but hesitant and looking for (potential) supporters before they are seen as voicing their opinion openly. If someone else falls for it and opens up, they then can just second them (with the confidence that they are not the first to face the consequences, if any).
test the water: Judge people's feelings or opinions before taking further action.
This is called a
"Who's buried in Grant's tomb" question
You can also react to the question, after you or someone else has asked it, by saying
to show that you just realized the answer was obvious. This is a fairly recent thing, and it might just be for the U.S., I'm not sure.
"Duh!" is usually said with a certain musical inflection in the voice, and may be accompanied by a heel of the hand tap to the temple. Optional variant:
Edit: one more -- a vapid question
(offering nothing that is stimulating or challenging)