Use this method only for non-cPanel control panel servers.

Step 1:  cd /etc/sysconfig/network-scripts

Step 2: cp ifcfg-eth0 ifcfg-eth0-bahhh

Step 3: nano ifcfg-eth0-bahhh
(and fill in this:)

DEVICE=eth0
BOOTPROTO=none
HWADDR=xx:xx:xx:xx:xx:xx
ONBOOT=yes
TYPE=Ethernet
NETMASK=255.255.xxx.xxx
IPADDR=xx.xx.xx.xx
GATEWAY=xx.xx.xx

Step 4: Restart the network $ ]  /etc/init.d/network restart

Done.

Add IP range

IPADDR_START=xxx.xxx.xxx.10
IPADDR_END=xxx.xxx.xxx.100
CLONENUM_START=0

cPanel – Control Panel Servers:

This can be easily done using the WHM interface: go to
IP Functions/Add a New IPAddress.

Here you can choose the “Ip(s) to add” and the Subnet Mask.