DNS PTR record explained

DNS PTR record – What is it?

DNS PTR record is a type of DNS record, which is oftentimes called pointer record. This is because it helps to associate an IP address to a domain name. The goal is to show that the specific IP address is actually related to the domain name. If somebody is checking it, this record proves that there is no scam. With the DNS PTR record it is easy to validate the different elements or additional services, such as a mail server.

What is inside it?

Inside the DNS PTR record is a very simple structure. However, in case you want to create one, you are going to notice some fields, which are the following: 

  • TYPE: In this case, you should choose PTR.
  • Host: Here, you have to type the IP address. It could be both an IPV4 address or an IPv6 address. 
  • Points to: Here, you have to type the domain name. 
  • TTL: Here, you set the TTL (time-to-live) value of the PTR record. Typically, it is not mandatory to be low.

How to create your DNS PTR record?

Creating your DNS PTR record is an easy task. So, let’s describe it in several steps.

First, you have to create a Master Reverse Zone.

The PTR record is able to exist in a Master Reverse Zone. Note that it should not be placed in a standard Master zone. Whenever you make the Master Reverse Zone, the IP address should be in reverse order. So, for illustration, if the IP address is 1.2.3.4, you want to add it as 4.3.2.1. The same rule applies no matter if it is an IPv4 address or IPv6 address. 

Second, you have to create the PTR record.

When you are adding the PTR record, you will have to type it in reverse too. For every one of your PTR records, you should have a matching A or AAAA record. So, make sure to check!

Lastly, add NS records.

You should add NS records at the IP provider, which are pointing to your nameservers. Finally, your Reverse DNS zone is completed!

How to check it?

If you want to check your DNS PTR records, you have to perform a reverse DNS lookup.

On Linux and macOS

Inside the Terminal, use the dig command. 

Type:

dig –x 1.2.3.4

On Windows

Inside the Command Prompt, use the nslookup command. 

Type:

nslookup 1.2.3.4

*Place the IP address that you require to view.

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

Why use the DNS PTR record?

DNS PTR records provide trust and verify IP addresses as a key part of the Reverse DNS. Therefore, if you desire your outgoing mail servers to run accurately, you should add such records. The reason for that is the verification methods that demand them. For example, by that particular method, if there is something suspicious, the email ends up in SPAM. Other examples are if the searcher does not locate a DNS PTR record or the PTR does not meet an A/AAAA record adequately. Therefore, you will want to add DNS PTR records in a Reverse DNS zone if you require to send emails. Moreover, these emails reach their addresses. 

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