How do I create a reverse DNS (PTR) Record
I have an Ubuntu 18.04 droplet being used as a web host for a shared hosting setup. I need to set up a Reverse DNS record for the Web Host as outgoing emails from the hosted sites are being rejected by recipients as the server does not have Reverse DNS setup.
Unfortunately, I did not name the droplet with a FQDN, just a descriptive name: should I do this? If so, I cannot see how to name/rename the Droplet in the Digital Ocean Control Panel.
Also the DNS for the Host Servers domain is not located in Digital Ocean, but in a third party DNS hosting service, and I don’t really want to move it.
So, how do I set up a Reverse DNS record under these circumstances?