Is question mark optional?

Could somebody please help? Thanks.

It is a question, so I think the question mark is necessary.

I suppose there might be a case where those words could be more of a "command from a superior" than a "question from a colleague". But that would not be a typical reading of such a sentence.

I don't understand your answer.

It is a question, so I think the question mark is necessary.

There could be exceptions, but those exceptions would not typical readings of such a sentence.

The question mark is absolutely required.

Thanks to both of you.