[CentOS] Network and default route

I have had this problem on and off since RedHat 6, and I always worked through
it, but I thought I would ask.
When you have multiple network interfaces, how does the system determine the
default route?
Or is it the first, (or last) interface that comes up?

On the problem systems I have to add a "route add default..." statement in
some systems in the rc.local to get them to work right.


-- 

MailScanner is like deodorant...
You hope everybody uses it, and
you notice quickly if they don't!!!!