How to configure reverse DNS
This article describes what reverse DNS is, when it is used, and how to configure it for your account.Table of Contents
- What is reverse DNS?
- Testing reverse DNS
- Configuring reverse DNS
- More Information
What is reverse DNS?
IP addresses are resolved to domain names by reverse DNS lookups, also referred to as reverse DNS resolution or rDNS. Regular DNS resolution, commonly referred to as forward DNS lookups, takes a domain name as input and returns the IP address associated with it. This is the opposite of what happens here. Reverse DNS lookups employ PTR records to identify the domain name associated with an IP address, whereas forward DNS lookups use A records to find the IP address connected with a domain name.
As an anti-spam measure, external e-mail servers frequently require sending domains to have PTR records. If a sending domain does not have a PTR record, the e-mail server rejects the message, usually with an error message in the SMTP headers indicating that reverse DNS is not configured.
Testing reverse DNS
To determine if there is a PTR record associated with a particular IP address, you can log in to your account using SSH and then type the following command. Replace xxx.xxx.xxx.xxx with the IP address that you want to test:
Copydig -x xxx.xxx.xxx.xxx
For example, if you type the following command:
Copydig -x 75.98.175.166
You receive the following output:
;; QUESTION SECTION:
;166.175.98.75.in-addr.arpa. IN PTR
;; ANSWER SECTION:
166.175.98.75.in-addr.arpa. 42989 IN PTR 75.98.175.166.static.hostventowebhosting.com.
This output shows that IP address 75.98.175.166 is associated with the domain name 75.98.175.166.static.hostventowebhosting.com.
Configuring reverse DNS
If you have a VPS or dedicated hosting account, we can set up reverse DNS for you. To do this, please open a support ticket on the Customer Portal at https://secuire.hostvento.com. In the ticket, please specify the domain you want to configure for reverse DNS, as well as your account’s IP address.
Shared and reseller servers already have reverse DNS configured for the main IP address. If you find that this is not the case for your account, please open a support ticket and let us know. Make sure you include your domain name and IP address in the ticket. If you have a dedicated IP address we can set up reverse DNS for you. To do this, please open a support ticket on the Customer Portal at https://secuire.hostvento.com. In the ticket, please specify the domain you want to configure for reverse DNS, as well as your account’s IP address.
More Information
For more information about reverse DNS, please visit http://en.wikipedia.org/wiki/Reverse_DNS_lookup.
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