Reverse DNS
Reverse DNS, also called rDNS, is used by email servers to verify that email has arrived from a valid server before allowing incoming email into a network. point. rDNS is crucial for email deliverability and server reputation. For instance, web site contact forms often fail because Reverse DNS is not configured properly and emails are dropped before reaching a web site owner’s Inbox. This is why SPF, rDNS, DKIM, and DMARC are so important in business email.
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Click on the headers below to follow our guide to record a Reverse DNS/PTR record in your domain name’s zone record at your domain registrar. Click on images to see in full resolution.
How to prepare
If your DNS is managed using nameservers at a domain name registrar, you will need to create a Reverse DNS/PTR record in the zone record where you keep your domain name. If your domain name operates using our nameservers (i.e. ns1.namesfirst.net) you only need to check your zone record in cPanel by pointing to Domains > Zone Editor to determine if a record needs establishing.
Therefore, before you proceed, prepare as follows:
- if in doubt, check with us where your records need modifying
- find your cPanel login credentials from our server information sheet
- (optionally) find the login credentials for your domain name supplier
If you are nervous about dealing with this technology, we can provide admin support for domain names and ongoing services – ask for help.
Step-by-step instructions
This workflow assumes that your domain name is managed at the domain name registrar where you manage and renew your domain name. If you are unsure where your DNS zone is managed, contact us.
1. Understand Reverse DNS:
- rDNS maps an IP address to a domain name
- It’s the opposite of the usual DNS lookup
2. Find out your web server’s IP address:
- your server’s IP address in displayed in your cPanel home page (usually towards upper right)
- make a note of the address
3. Log in to your domain name supplier:
- raise a support ticket asking for rDNS and providing the following:
- the IP address you noted in 2 above
- the PTR value for the PTR field – usually, this would be mail.yourdomain.com
- if your supplier asks for more information – there are a few ways to create this record
- expect up to 24 hours for the record to work
4. Verify rDNS:
- use a resource like MXToolbox to verify your IP address resolves to mail.yourdomain.com
- if necessary, follow up with your ISP
Summary
Reverse DNS is an important tool that remail servers rely on to verify that email you send is recognized as valid. Without this validation, you may send email that is rejected or dropped before it reaches a recipient’s Inbox.
Making adjustments to your domain name’s zone record requires exacting language and syntax. A missing character can cause a web site to cease functioning and disable your organisation’s email. Nor can you test a modification first – changes made have effect in real time.
Expert help available
We have decades of experience managing domain names on behalf of clients. If you are nervous about dealing with this technology, we can provide admin support for domain names and ongoing services. We can turn modifications in minimal time at reasonable cost while saving you from risk of web site and email disruption – please ask for help if in doubt.