How do I configure rDNS if I'm using CloudFlare?
I can not configure rDNS when using CloudFlare.
No match was found. Reverse DNS must have a matching forward entry.
I have checked all A and AAAA records point to my Linode's IP.
Can you help me?
In order to configure rDNS, you first need A and AAAA records that point your domain to the IP you'd like to configure. The trouble with Cloudflare is that it hides your IP, so when we attempt a forward lookup on your domain, we see CloudFlare's IP instead of your server's IP.
The way around this to configure a subdomain that is not hidden behind CloudFlare, point it to your Linode's IP, and then configure rDNS. For example.com, it could look like this:
example.com (orange cloud indicating it is behind CloudFlare)
mail.example.com (grey cloud indicating it is not proxied by CloudFlare )
Make sure to point mail.example.com to your Linode's IP. If you want rDNS for your IPv6 address as well, be sure to create an AAAA record for the mail.example.com as well.
This is also the recommended approach because CloudFlare does not proxy incoming emails, so you do not want your email server hidden behind CloudFlare.
For more reading and resources on this, I'd recommend the following:
Managing DNS Records Behind CloudFlare