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What is Reverse DNS (rDNS)?

As an email marketer, your priority should always be to ensure that you can consistently reach the inboxes of your recipients, as this ultimately determines the potential success of your campaigns. To this end, it is essential to make the process as easy and secure as possible for your recipients.

Fortunately, there are numerous measures that you can take to do this. By enabling certain features in the DNS (Domain name System), inbound mail servers can more easily verify your identity as a sender, providing increased security for users and improving your delivery rate.

One example of such a feature is rDNS.

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What is rDNS? The benefits of rDNS Security and deliverability
Marketing performance
How to set up rDNS Conclusion

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What is rDNS?

Reverse DNS, or rDNS, is a querying technique used with the DNS (Domain Name System). With standard “forward” DNS lookup, a domain name is used to query the DNS to locate an IP address. However, rDNS works in reverse, instead querying an IP address to resolve a domain name.

When receiving an email, a recipient mail server can use rDNS to query the IP address against the DNS. It then locates a pointer record (PTR), which links the IP address to the hostname. This allows the server to find the hostname and determine the origin of the message.

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The benefits of rDNS

Reverse DNS lookup plays an important role both for marketers and email users, for the following reasons:

Security and deliverability

Reverse DNS lookup is frequently used by receiving email servers as a security measure. When handling incoming email, mail servers use the IP address of the sender to check the validity of the sender before allowing the message through to their network. 

In this way, rDNS has a similar function to authentication protocols such as SPF, DKIM, DMARC, in that it is used to help verify the identity of a sender.

In many instances, a mail server may reject messages originating from a server where rDNS is not supported for fear that the sender may be a spammer. To avoid this, set up rDNS, as it can help you to reach the inboxes of your audience with greater consistency.

Marketing performance

Aside from the security aspect, having rDNS set up on your domain can be a genuine asset from a marketing perspective. This is because it can enable you to retrieve data about those who visit your company site, providing information about visited pages, site interactions, and much more.

By using rDNS to gain access to this data, you can use the insights you glean to inform your email marketing initiatives, allowing you to generate leads more easily and create targeted campaigns that result in more conversions for your brand. This is especially useful for B2B as companies often use dedicated IP addresses that can yield deeper, more actionable insights.

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How to set up rDNS

Though it may  seem difficult, setting up reverse DNS is a relatively simple task. You can set up rDNS by following these steps:

  1. Contact the party that owns your IP block, usually an ISP (Internet Service Provider) or hosting provider, and request a zone for your reverse DNS. This should end in “in-addr.arpa,” and display a reversed IP block.
  2. Create your reverse DNS zone. Remove the final digits from your IP address, then reverse the octets that remain. Finally, add ‘in-addr.arpa’ at the end of the sequence.
  3. Request that your ISP delegates rDNS to the relevant DNS provider.
  4. Set up your reverse DNS zone by logging into your account with the hosting provider and accessing the DNS menu. From there, add the name of the reverse DNS zone.
  5. Create a PTR record. Access the control panel in your account and locate the appropriate PTR record setting. There, add the last digit of the IP as the name, and the relevant domain name as the canonical name.

Upon completing these steps, you may need to wait 24 hours or more for your changes to take effect. There are also tools available to help you complete the process if you encounter difficulty.

Conclusion

Reverse DNS, or rDNS, is a querying method that uses an IP address to determine a domain name. It functions in reverse compared to standard DNS lookup, hence the name.

Reverse DNS has an important part to play in email communication, especially as a marketer, as it helps recipient mail servers verify the origin of incoming mail, thus improving your delivery rate. Moreover, when used effectively, rDNS can be a powerful tool with which to gain actionable market insights.

By setting up rDNS, you can craft more targeted marketing content and ensure that your emails get where they need to go, improving the success rate of your campaigns.

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