Knowledgebase: Dedicated Servers
What is a reverse DNS entry (rDNS) and why do I need it?
Posted by Help Desk (6), Last modified by NOC Desk Monitors on 07 August 2018 11:42 AM
A DNS normally consists of â€˜Forwardâ€™ lookups such as A records. An example of this would be the domain name â€˜helpdesk.hostnetworks.comâ€™ has the A record of 220.127.116.11.|
A Reverse DNS entry, known as a PTR (Pointer) record does the opposite and matches the IP to the domain name.
So using the above example, performing a reverse DNS whois lookup of 202.174.00.9 results in helpdesk.hostnetworks.com.
This is found by asking the name servers responsible for the IP address.
For this to work a forward record must exist and match the PTR record. If the PTR record does not match the Forward record then errors will occur.
Why do I need a rDNS entry?
Just about every mail server on the internet uses a basic check to verify that the sender is legit and isnâ€™t spam. It does this by checking that a rDNS entry exists for the IP sending the email. If it doesnâ€™t the mail will bounce.
This is only required on the IP sending email and isnâ€™t required for every IP address you may have with your service.
How to get an Reverse DNS PTR Record added?
Simply lodge a ticket in the helpdesk asking for a PTR record to be created for x.x.x.x (IP Address) with the name X.X.X (A valid A record you have setup for that IP).