Setting up rDNS

Introduction

rDNS, or reverse DNS, is just the reverse process of forward DNS. DNS, or Domain Name Service, is a process that translates a human readable URL or domain name into an IP address for a computer to read. rDNS is used when you have an IP address and need to find the domain name. Setting up DNS and rDNS makes a domain more trustworthy and traceable, by matching the domain against the IP it is coming from and validating it.

How to set up rDNS

Even though rDNS is the reverse of normal DNS, the setup is not the same process in reverse. An rDNS query will yield a Reverse Pointer or PTR record. The first thing to do is create an rDNS zone on your server. It is important that the zone is created on the authoritative DNS nameserver for the main IP address of your server. Your hosting provider may already have this setup, but if you have authoritative control of your nameserver, you can do this yourself. The format for your zone hostname is very specific.

  1. Take your IP address, drop the last set of numbers (the last 3), reverse the remaining numbers and add .in-addr.arpa. to the end.
  2. Now that you’ve created your zone file, you can create the PTR record. Add a new PTR record and enter the final number set of the IP address that you’re setting up the reverse record for as the name of the record. This will be the set of numbers that you removed for your zone hostname.
  3. Then enter the domain name you want the IP address to resolve to under Canonical Hostname. Save the zone file and wait for the changes to show.
  4. The final step is validating your rDNS record to ensure it is correct. You can run the DIG Web Interface Tool to do this. A record that links the zone file you created with the domain name you entered shows that the setup was successful.

Make sure your DNS and rDNS are setup with Cloud.co.za

rDNS is often used by mail servers, ISPs and anti-spam software to ensure that a domain is fully validated. Validated domains are indications that a site is reliable and authentic, helping boost your online credibility. If you need any assistance with setting up rDNS, contact Cloud.co.za today.

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