How to restrict user to post questions in space only for confluence?

[kunjiraj]

Related to question, user should not post question which are visible to all other space user as in default it is.

here i see user need to explicitly select space to restrict that question.

Is there anything which can restrict user to post question on confluence level and user can post it in space only where he has access.

[Mirek]

Basically there is a Add Comment space permission that control who can add comments on specific space, so we can see who have access and at the same time restrict the ability to comment. 

Here is an overview of all space permissions

https://confluence.atlassian.com/doc/space-permissions-overview-139521.html