questions about cron.daily

[coreyh@free.fr]

Hello list,

For scripts put under /etc/cron.daily, which special time will they be 
implemented?

I know they will be run daily, but not sure about the special run time.

And, I found some services like apache2, chkrootkit will put the scripts 
in this dir automatically. are they for system cleaning purpose?

Thanks.
Corey