Hi, @djmtype. Let’s say you have a static public IP address at DigitalOcean of 10.9.8.7 (yes, “ten-dots” are not public IP addresses - but let’s pretend).
If you want
sub.mydomain.com to point to that IP address, you would make an A record for that name and IP address which would look something like this when queried:
sub.mydomain.com. 1800 IN A 10.9.8.7
You might instead have a domain name and not an IP address to point to.
Let’s say the Wordpress install is at
wordpress.example.com and you want to use that name instead of the IP address. If so, you would make a CNAME record instead:
sub.mydomain.com. 1800 IN CNAME wordpress.example.com.
Note, if you want to connect via HTTPS/SSL, you will need to install an SSL certificate on the Wordpress instance itself.
SSL is handled via HTTP not DNS. This means that the web server you point to (the Wordpress host) must provide the SSL for that subdomain.
If there are other questions about this, please let us know.