Toilet clogged, sound coming from bathroom sink when toilet flushes, main drain in basement 100 years old

What can I do when the bathroom sink makes air sounds when the toilet is flushed?

Is the drain in the basement clogged?

Hi Pkrotzer

I am afraid that I am confused by your 2 posts as they completely state different factors so I really don't know where to start.

Could you please post the correct information here at this thread.

Thanks!

Mark