Reverse DNS Lookup
Use this reverse DNS lookup to find the PTR name of an IP address. It also checks that the name resolves back to the same address, which receiving mail servers expect from a sending server.
The Uptrack server reads the records through the public DNS resolver of Cloudflare and follows every include for you. A check can take a few seconds.
Try an example
Reverse DNS lookup: what a PTR record is
A normal DNS record maps a name to an IP address. A PTR record maps an IP address back to a name. Mail servers use it as a first trust check: they ask who an address is before they accept mail from it.
Only the owner of the IP address can set its PTR record, usually your hosting provider. You set it in the provider’s panel or ask their support.
PTR record check: forward-confirmed reverse DNS
- The name
- The PTR name of the address, for example mail.example.com.
- Forward confirmed
- The name resolves back to the same IP address. This is the check receivers run.
- A generic name
- Hosting defaults such as a long number in the name tell receivers nobody chose the name. A name you own, such as mail.yourdomain.com, is trusted more.
- The same name in EHLO
- A mail server should also say this name when it connects. Check it in the Received header of a message it sent.
Frequently asked questions
What is a reverse DNS lookup?
It starts from an IP address and finds the name stored for it in a PTR record. It is the opposite of a normal DNS lookup, which starts from a name and finds the address.
Why do mail servers check reverse DNS?
A sender with no PTR record, or one that does not match, is more often spam. Many receivers score such mail as suspicious or refuse it.
How do I set a PTR record?
Ask the owner of the IP address, which is usually your hosting provider. You cannot set it in your own DNS zone. First make sure the name you want has an A record that points to the address.
What is forward-confirmed reverse DNS?
The IP address has a PTR name, and that name has an A or AAAA record that points back to the same address. Both directions agree, so the name is hard to fake.
Can an IP address have more than one PTR record?
Technically yes, but it is better to keep one. Some receivers read only the first, and the order is not fixed.
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