How to perform Reverse DNS lookup in Linux?

Reverse DNS lookup is another interesting topic that is not often discussed. As a Linux user, you have several different options to perform it. So, let’s talk a little bit more about it and how you can do it.

Reverse DNS – What is it? 

Reverse DNS or rDNS is a very beneficial service that supplies Reverse DNS zones for your domain name. The Reverse DNS zones are required for storing PTR records which are utilized for verification purposes. For instance, to check the IP address and if it points to the proper hostname.

Your recipients’ mail servers that desire to send you messages have to ensure that the IP address that they are viewing actually belongs to your domain name. If not, they could send the messages to a different place. Unfortunately, that makes space for criminals to take advantage of that information.

Another common way to use it is for verifying different services and the specific IP address that really refers to the domain name. 

The Reverse DNS works perfectly to point IPv4 addresses or IPv6 addresses to hostnames. In addition, you are able to add both PTR records with IPv4 and IPv6 addresses within the same Reverse DNS zone.

Why is it important?

The Reverse DNS is important because your messages probably will not arrive at their proper destination if you are not implementing it. The receivers’ mail servers are going to examine for your PTR records within other DNS records. In case they don’t discover them, the receivers would probably not trust your domain. In addition, they will reject any emails you are sending to them.

What is a PTR record?

The PTR record, also known as a pointer record, is a DNS record type that you can implement for Reverse DNS. It points IP addresses, both IPv4 addresses, and IPv6 addresses, to the domain name. 

Once the receiving mail servers require to examine the origin of the message, they are going to complete a DNS Reverse lookup. In which they are going to search for the PTR records. With them, you are able to ensure that the IP address is for sure belonging to your domain name.

Reverse DNS lookup for Linux

As a Linux user, you have several different options for completing a Reverse DNS lookup. So, just open the Terminal and try out these 3 commands that could be used for that purpose. 

Nslookup command

Nslookup is the first command that you can use to complete a Reverse DNS lookup. In this example, type the following:

nslookup 123.45.67.89 

*Make sure to change the IP address with the one you would like to check.

Dig command

Dig is another very beneficial tool for Linux users. To perform Reverse DNS lookup, you just have to type the following inside the Terminal:

 dig -x 123.45.67.89

*Make sure to change the IP address with the one you would like to check.

Host command

The third command that you can easily use is the host command. To perform ​Reverse DNS lookup, simply type:

host 123.45.67.89

*Make sure to change the IP address with the one you would like to check.

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