NIC tries to Start on boot but fails
 

When I start Redhat 7.2 and it goes through its startup routine, it tries to start eth0 but then I get the red FAILED message. I really don't want it to start on startup. How do I change it so that it doesn't even do this? Thank you.

I found out how, but why
 

I found out that I can stop it from coming up by editing /etc/sysconfig/networking/devices/ifcfg-eth0 and /etc/sysconfig/network-scripts/ifcfg-eth0 so that ONBOOT=no. What is the difference between the two files??

use the one in network-scripts
removing the card will cause kudzu to notice it and remove those scripts for you.
Otherwise you can remove link in
/etc/rc3.d/S10network and
/etc/rc5.d/S10network