How to configure Reverse DNS
To modify the Reverse DNS (rDNS) of our server we will enter our client panel and go to the DNS and PTR Records tab. There we will see a list with all the IPs of our servers, we will click on the pencil of the IP that we want to modify the reverse DNS.
Reverse DNS Explanation
Well, to tell you roughly, the reverse DNS or rDNS basically does the opposite of the “normal” DNS. That is, instead of resolving a domain name to an IP, it resolves an IP to a host name.
Reverse resolution or rDNS is completely separate from regular DNS resolution, so for example, if the domain “yourdomainname.com” points to IP 1.1.1.1 (dummy IP), it does not necessarily mean that the reverse resolution for the IP is 1.1.1.1
To store the reverse resolution records, a specific type of DNS record is used: the PTR record.
The PTR record is the resource record (RR) of a domain that defines the IP addresses of all systems in an inverted notation.
This inversion allows an IP to be looked up in the DNS, since the in-addr.arpa domain is added to the inverted IP notation, converting the IP into a domain name. For example, to convert the IP address 11.22.33.44 into a PTR record, we invert the IP and add the domain in-addr.arpa, the resulting record being: 44.33.22.11.in-addr.arpa.
Although the most common operation with the Domain Name System or DNS is to obtain or resolve the IP address from a name; sometimes we want to do the opposite operation, to find the name of an element connected to the Internet from its IP address. This process is known as reverse resolution or rDNS.
The configuration of reverse DNS resolution is important for a particular application, because many mail servers on the Internet are configured to reject incoming emails from any IP address that does not have reverse DNS.
Therefore, if you use your own mail server on your Cloud Server you must have reverse DNS for the IP address from which the outgoing mail is sent.
It does not matter which IP address the reverse DNS record points to as long as the domain is hosted on that server. If you host multiple domains on an email server, you simply configure reverse DNS for whichever domain name you consider to be the priority.
We hope we have helped you with this article. If you have any questions about this or any other issue related to your Clouding servers, please write us at soporte@clouding.io. We are here to help! 😉