Reverse DNS PTR to naked domain?

Forum Moderators: phranque

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Reverse DNS PTR to naked domain?

jay5r

3:26 pm on Sep 22, 2022 (gmt 0)

I've heard, and read references to, the fact that you shouldn't specify a naked domain when setting up a Reverse DNS - that you need to specify a subdomain. Is this true?

For example:
Supposedly Bad: exampledomain.com
Good: www.exampledomain.com

What exactly goes wrong when you point to a naked domain?

The reason why I'm asking is because using naked domains for website addresses is more common than it was in the past, and IPv6 makes it so every website can have it's own IP. So I would think it would make sense for the canonical URL to be the same as the reverse DNS for IPv6.

phranque

12:23 am on Sep 30, 2022 (gmt 0)

PTR records are the inverse of A (or AAAA) records.
therefore, if your A record points to the root domain, the inverse PTR record must also be associated to the root domain.

jay5r

12:18 pm on Sep 30, 2022 (gmt 0)

PTR records are the inverse of A (or AAAA) records.
therefore, if your A record points to the root domain, the inverse PTR record must also be associated to the root domain.

But multiple A (or AAAA) records can point to the same IP, so it's not quite so simple.