How to add additional IP address on CentOS servers.
Create file: /etc/sysconfig/network-scripts/ifcfg-eth0:0
DEVICE="eth0:0" BOOTPROTO=static ONBOOT=yes TYPE="Ethernet" IPADDR=80.80.25.25 #HWADDR=00:0C:29:28:4C:4C #GATEWAY=80.80.25.1 NETMASK=255.255.255.0
do this for each additional IP address, you only need to increase virtual interface number by one for each additional IP.
Like eg. eth0:1, eth0:2, eth0:3 ...
**if you don't have HWADDR then delete that line.
Restart Network
service network restart
Check all IP's configured on the server
ifconfig
if your new IP address is listed then you have successfully added a new IP address.