I was trying to add a second IP address to eth0.
I have done this in the past on RH5/CentOS5
I would cp ifcfg-eth0 to ifcfg-eth0:1 and then change IP and change device name to eth0:1
If I do that on centOS 6 and do a service network restart, it does not even try to start it.
If i manually do this at command line:
ifconfig eth0:1 192.168.110.80 netmask 255.255.255.0 up
It works, but I want to make sure if server restarts it will start it up automatically.