Air coming from floor drain

I live in a basement apartment of a house and there is a drain in the floor of my bathroom. If I put my hand above the drain, I can feel a cool draft of air coming up from the drain. Sometimes I notice that there is a slight bad smell (not terribly strong) coming from the drain and filling the bathroom as well.
Is this normal, or is it something to be concerned about? What could be causing this, and how can I fix it?
Any replies are appreciated!
Thanks!

The trap in the floor has likely just dried up. I have the same problem in a drain in my basement. During the dry months, I just pour a bucket of water down it once every few weeks and that takes care of the problem.

It could also be that the trap is cracked/broken (remote chance).

If the trap has dried up, sewer gas can travel back up the floor drain.