cPanel and Remote MySQL Server should be able to use private IPs
Typically the cPanel server is public-facing which means it's hostname resolves to a public IP address. There is a strong use case to want to connect a remote MySQL server using a private network interface. However, the MySQL server can only resolve the cPanel server's hostname to it's public IP address which means the DB user accounts created on the MySQL server are given grants to the wrong IP address.
The work-around is to grant privileges on the private IP address manually. But in a shared hosting environment where accounts can be provisioned automatically this would pose a problem. It would useful for cPanel to support remote connections to MySQL using private IPs.