Symptoms
When you try to add your server's private IP address in the Confirm the IPv4 address to create an A record field on the Configure Address Records page in WHM, the system converts the private IP address to the server's public IP address.
Description
When the server is running in NAT (Network Address Translation) mode, the system uses the server's public IP address as the nameserver IP address. The system does this so that external servers can query your server's nameserver on its public IP address.
Additional Information
You can read about NAT configurations here: