What is Reverse DNS?

Reverse DNS is a method of mapping domain names to IP addresses. It is most often used for websites with a large number of domains, where the content management would be too cumbersome if each subdomain had its own website. For example, you could use reverse DNS to map www.example.com to an IP address like 172.31.110.221 by typing in that information into your browser bar or URL bar instead. Reverse DNS mapping can also be used on other types of servers, such as mail servers and SSL/TLS certificates, wherein the domain name is mapped to an IP address for troubleshooting purposes and management workflows respectively by adding xn-reverse-dns entries to the server configuration files (e.g. /etc/hosts , /etc/resolv.conf , etc.) or by adding text records to the DNS console of your domain registrar service.

In order for reverse DNS to work, there are several prerequisites that all computers on the network must meet:

(i) Most importantly, each device on the LAN must have a globally unique IP address from which it is accessible by other devices also on the network.

(ii) The operating system and other installed software that runs on a computer’s internal hardware needs to support reverse DNS lookup functionality using appropriate APIs or libraries called by associated programs, such as web browsers and command-line utilities such as dig .