[CentOS] Init checking for processes that are configured to "respawn"

Hi folks,

I have a sophisticated question for which I can't find any hints on the 
web:

If you configure init (via /etc/inittab) to respawn processes (like the 
getty processes) when they exit - how often does init check for the 
existence of such a process? Does it check actively at all or does it 
rely on some kind of inter process communication?

I am not a programmer, so maybe the second question is completely 
nonsense. Any hint or help is appreciated.

Dirk