blimey, for such a widely used application, I find that incredible.
Whats even more ridiculous is the extent of Cloudflares article on DNS PTR records… so everyone can have a laugh I will post it in its entirety
DNS PTR Record
Learning Objectives
After reading this article you will be able to:
Understand the purpose of an PTR record.
What is a DNS PTR record?
The ‘pointer’ record is exactly the opposite of the ‘A’ record; the PTR address will give you the domain associated with a given IP address. The PTR record is used in reverse-lookup zones for reverse DNS searches.
Example of an PTR record:
example.com record type: value: TTL
@ PTR example.com 71200
The value here represents an email address ,which can be confusing because it’s missing the ‘@’ sign, but in an SOA record admin.example.com is the equivalent of admin@example.com.
what can one say?
Anyway, the ptr record is done for the server itself. So for example, if you were using Vultr.com as your VPS provider, then you would add the reverse ptr inside Vultr server dashboard/console.
I found another bit of information on cloudflare that will help you out with this…(sorry about the condescending way it starts, I am just copy and pasting it in)
How does reverse DNS work?
Reverse DNS lookups query DNS servers for a PTR (pointer) record; if the server does not have a PTR record, it cannot resolve a reverse lookup. PTR records store IP addresses with their segments reversed, and they append ‘.in-addr.arpa’ to that. For example if a domain has an IP address of 1.2.3.4, the PTR record will store that information as 4.3.2.1.in-addr.arpa.