Which sentence is correctly punctuated?

It seems to me, it would be, Do you know the man?. It's a question and I am not sure why there is an exclamation point being used in the examples you have given.

The first sentence is correctly punctuated.

The use of an exclamation mark along with a question mark is informal, non-standard punctuation. In an interrogative sentence use the exclamation mark to emphasize exclamation.