What is a DNS PTR record?

DNS PTR record is one of the essential DNS records. It is one of the few that deserve proper attention. So let’s explain a little bit more and get to know why it is so important.

DNS PTR record – meaning 

The DNS PTR record has a specific purpose. It is to point the IP address to the domain name. Therefore, it can operate successfully both with IPv4 and IPv6 addresses. Furthermore, this type of DNS record makes it possible for you to achieve Reverse DNS.

Receiving mail servers want to verify the source of an email. For this matter, they will do a DNS Reverse lookup, and they will investigate for PTR records. DNS PTR record makes it possible to guarantee that the IP address truly belongs to the domain name.

Why is it important to use a DNS PTR record?

DNS PTR records are responsible for providing trust and validating the IP addresses, as a fundamental part of the Reverse DNS. Therefore, if you want your outgoing mail servers to function correctly, you should add PTR records. That is because of the verification methods that, in most cases, require them. Through that specific procedure, if there is something wrong, the email will go to SPAM. Such examples are if the searcher does not find a DNS PTR record or the PTR does not match an A/AAAA record properly. Therefore, you will need to add DNS PTR records in a Reverse DNS zone if you need to send emails. Moreover, these emails actually reach their addresses. 

Structure

The PTR record is actually a simple DNS record. Here are the fields that you will notice:

  • TYPE: PTR
  • Host: Here is the IP address. (IPv4 and IPv6)
  • Points to: The domain name. 
  • TTL: It is not required the TTL value of a PTR record to be low.

How to create your PTR record?

Creating your PTR record is a simple and easy task. So, let’s explain it in a few steps.

First: Create a Master Reverse Zone

This is the zone of your domain where PTR records are able to exist. It is important to mention that it can not be created in a standard Master zone.

When you create the Master Reverse Zone, the IP address should be in reverse order. So, for example, if the IP address is 1.2.3.4, you simply need to add it as 4.3.2.1. Apply this same rule no matter if it is IPv4 or IPv6. 

Second: Create the PTR record.

The second thing you have to do is to add a DNS PTR record. You will have to create the PTR record in reverse too. Check if there is a matching A or AAAA record for every one of your PTR records.

Last step: You will have to add NS records at the IP provider, which are leading to your nameservers. This is the last thing required to complete your Reverse DNS zone.

How to check it?

To check your DNS PTR records, you will have to complete a reverse DNS lookup.

On Windows

Inside the Command Prompt, use the nslookup command. 

Write:

nslookup 1.2.3.4

On Linux and macOS

Inside the Terminal, use the dig command. 

Write:

dig –x 1.2.3.4

*Just change 1.2.3.4 with the IP address that you require to view.

If your query notices a PTR record, the result will be the domain name.

So now you know a little bit more about the PTR record, how to make it, and how to check it.