Please show me example sentences with の(ん)だ/ なの(なん)だ in questions. . Tell me as many daily expressions as possible.

See a translation

@Hopy: ooh I thought they could, look at this sentences please, they are part of another question I made but which no one has answered yet.

I've notice that certain questions in casual speech end with だ, for example:

何してんだ?
本当なんだ?
どこに行くんだ?

Are these types of questions with だ actually used in real life? If so, who can use it and to whom can be used?

@Hopy:

Ooh I see, so you would append だ just when you are angry? Or are there other situations?

@Hopy: Thank you very much for such a complete answer!! Because of your answer, it reminded me of a question I have always had and that I don't know the answer, you gave me these ways of asking questions:

何してるの？
どこに行くの？
誰といるの？
何しゃべってるの？
何を食べてるの？

So what I wanted to know is what is the difference if a ask the very same questions without の:

何してる？
どこに行く？
誰といる？
何しゃべってる？
何を食べてる？

I did some research and found out that it is not the same, for example, to say 行く?(Are you going?) or 行くの (It is that you are going? You are going? Are you really going? However, I don't know anything about questions with interrogative words plus の like the ones in the examples. Therefore, I don't know if there is a difference like the one I presented with 行くの. I'm sorry for so many questions but I really love your language! Thank you in advance!!

@Hopy: Got it!! I didn't know about that! Thank you!!