Ind v/s SL -> 4th ODI, Pune

Re: Ind v/s SL → 4th ODI, Pune

How many zones are there? And what is the Quota for each?
Does that mean if the quota is exhausted, a talented player cannot make it into the squad. I guess I heard that in such a case players try to get into the national side by switching their domestic teams or zones. I think Pathan or zaheer or some one else did that, I don’t remember exactly.