Hacker News Reader

They have "floating IP addresses" as droplet-agnostic IPs for exactly this purpose.

A floating IP address couldn't be used in my case because I needed a reverse DNS entry and "Floating IPs do not support PTR (rDNS) records."

Along with other limitations such as "we do not support IPv6 floating IPs. All floating IPs are IPv4" and "floating IPs do not support SMTP traffic"

https://www.digitalocean.com/docs/networking/floating-ips/

When would rDNS actually be useful?

It's probably a failure of imagination on my part that I can't think of a use case where I would want that.

Why not just use normal, forward DNS?

It's a requirement to send mail to some servers.

"Set up valid reverse DNS records of your IP addresses that point to your domain."

https://support.google.com/mail/answer/81126

Having functioning and accurate reverse-DNS is required for mail servers, as lots of mailservers reject mail from servers without correct reverse DNS. There's likely other protocols where having functioning reverse DNS is a necessity or strongly advantageous as well.

Reply on news.ycombinator.com