1. Login to cPanel Webhost Manager (WHM) on the server.
2. On the left pane, navigate to IP Functions menu, and then click on Add a New IP Address link.
3. Enter the IP address in the IP(s) to add field. Although the link says A IP Address, you can easily submit multiple or more than one IP addresses to be added to the server at once. For more than 1 IP address, specify in Class C CIDR format or 192.168.0.1-254 format. For example, 192.168.4.128/25, 192.168.3.5-10, 192.168.99.55-230.
4. Alter the subnet mask default value of 255.255.255.0 to the valid value for the IP address(s) in the Subnet Mask field, if required. Normally this value will be provided by your hosting provider.
5. Click on Submit button