.A "Domain IP" is using a domain name (something.com) to redirect to the actual server IP to connect to the server. Do note that this is NOT changing your IP, but giving an extra means of connecting to the Minecraft server. You can register your own domain a place like NameCheap.com which is a popular domain registrar.
Setting up a Domain IP requires you to have a Unique IP Address set for your server. See more about Unique IP Addresses here.
Once you sign up for a domain, follow these steps to have your domain connect to your server:
Domain > Manage Domains > Click on "yourdomain.com" > All Host Records >
HostName: @ > IP Address: Server IP without port > Record Type: A (Address)
HostName: www > IP Address: Server IP without port > Record Type: A (Address)
If you want to setup a "sub-domain IP" such as (something.yourdomain.com) follow these steps:
Domain > Manage Domains > Click on "yourdomain.com" > All Host Records >
HostName: something > IP Address: Server IP without port > Record Type: A (Address)
