Adding a subdomain to the DNS Manager
Head to your zone file and click
Add a new A/AAAA record
You can then enter your subdomain in the
Hostname field. For example, if you're setting up a mail server you might place
After that, add your IP address to the
IP Address box, change the
TTL if you'd like (leaving it as default is fine), and then click save. Once your new record has a chance to propagate the subdomain will start working.
Our DNS Manager guide covers how to add a record in detail.
As a side note, don't forget that you also need to configure your web server or mail system so that it actually uses the subdomain. How you do this depends on exactly what you're running.