DNS PTR record
(also DNS pointer record)
DNS PTR record definition
A DNS PTR record is a type of DNS record that provides the domain name that is linked to a certain IP address. So through a DNS PTR record, you can find out the domain name of an IP address. For example, if you only know the IP address of a certain site, you can find the site’s actual name (domain name) through a DNS PTR record.
The DNS PTR record is the exact opposite of a DNS “A” record, which provides the IP address linked to a certain domain name. And since the DNS PTR record is the opposite of a DNS “A” record, an “A” record should exist for every DNS PTR record. DNS PTR records are also used for the reverse DNS lookup.
In addition, outgoing mail servers use DNS PTR records so that the emails sent through the mail servers aren’t flagged as spam. All emails from mail servers that don’t use DNS PTR records are marked as spam because a DNS PTR record is necessary to prove that an email address or domain is valid.
See also: DNS record, domain
DNS PTR record use cases
- Security. If the email addresses that you communicate with don’t have a DNS PTR record, it means that their domains aren’t validated, and they might be risky. Such email addresses might send you spam or links that could infect your devices with malware.
- Validation. Having a DNS PTR record shows others that your domain and IP address are valid and shows them that your emails aren’t spam and don’t have bad intentions.
- Investigation. You can use a DNS PTR record to see where certain traffic originates from, especially if the system through which the traffic was created only stores IP addresses and not domain names.