Change Host Name Assistant
Use the Change Host Name Assistant to change the host name, computer name, IP address and—if your server has multiple Ethernet connections—the network connection.
When you make changes within the assistant, it automatically updates services that depend on the host name or IP address. It doesn’t update DNS records; you must update those in the DNS pane of the Server app.
You can obtain a domain name for your server from a public domain name registrar. For more information, see Register the server’s Internet host name.