Explanation

[james_chew_84]

I need an explanation on when to use

1) do you know him?
2) don't you know him?

Thank you.

[Casiopea]

I need an explanation on when to use

1) do you know him?
2) don't you know him?

Thank you.

Question 1) requires a Yes/No answer in response, whereas question 2) requires an explanation in response. 2) means, Why is it that you don't know him? Gee, you should know him, or at least, I thought you knew him. 2) is somewhat awkward pragmatically. The person it's directed to might take it as a judgement i.e., why are you questioning what I know and what I don't know?