Infrastructure

PTR RecordPointer Record

Definition

A PTR record (pointer record) maps an IP address back to a hostname, the exact reverse of an A record. It is what makes a reverse DNS lookup possible: ask “who is 203.0.113.10?” and the PTR answers mail.example.com. Defined as DNS type 12 in RFC 1035, it lives in a special reverse zone and is set by whoever controls the IP, usually your hosting provider.

  • Maps an IP address to a hostname, the reverse of an A record
  • Lives in a special reverse zone (in-addr.arpa for IPv4)
  • Set by the owner of the IP block, usually your host or ESP, not in your normal DNS
  • Required by Gmail and Yahoo on every sending IP since February 2024
At a glance
Record type DNS PTR (type 12)
Maps IP address to hostname
Defined in RFC 1035 (1987)
IPv4 zone in-addr.arpa
IPv6 zone ip6.arpa
Set by The owner of the IP block

How a PTR record is structured

An A record answers “what IP does this name point to?” A PTR record answers the opposite: “what name does this IP point to?” To make that lookup work, the IP is reversed and placed under a special domain. The IPv4 address 203.0.113.10 becomes the name 10.113.0.203.in-addr.arpa, whose PTR record holds the hostname. IPv6 uses the ip6.arpa zone in the same reversed style.

The catch is who controls it. Forward records like A and TXT sit in your own DNS zone, but the reverse zone belongs to whoever owns the IP block: your hosting provider, cloud platform, or email service. That means you usually cannot set a PTR yourself; you request it from your provider, often through a control panel field labelled “reverse DNS” or “PTR.”

A PTR record in the reverse zone for 203.0.113.10 
10.113.0.203.in-addr.arpa.   3600   IN   PTR   mail.example.com.

Why mail servers insist on a PTR record

When you connect to deliver mail, the receiving server takes your IP and runs a reverse DNS lookup on it. A missing or generic PTR (something like 203-0-113-10.dynamic.isp.net) is a classic spammer fingerprint, because legitimate mail servers have a clean, dedicated hostname. Worse, the better receivers do not stop at the PTR: they take the hostname it returns and resolve that back to an IP, checking it matches. That round trip is forward-confirmed reverse DNS.

This stopped being optional in February 2024, when Google and Yahoo began requiring every sending IP to have a valid PTR whose hostname resolves back to the same IP. Without it, bulk mail is rejected or filtered. You can confirm yours with our reverse DNS checker.

How a receiver checks your PTR record

Your server connects from 203.0.113.10 to deliver mail
The receiver looks up the PTR record for that IP
Is there a PTR, and does it return a real hostname?
No PTR: looks like spam Generic ISP name: weak signal Clean hostname: good
The receiver resolves that hostname forward and checks it points back to the same IP
Forward and reverse match, so the connection is trusted

PTR record vs A record

A record PTR record
Direction Hostname to IP IP to hostname
Lives in Your forward DNS zone The reverse zone (in-addr.arpa)
Who sets it You / your DNS host The IP block owner / your provider
Email role Resolving mail servers Reverse DNS and FCrDNS

By the numbers

Type 12
The DNS record type number assigned to PTR records in RFC 1035.
Feb 2024
Since this date Gmail and Yahoo require a valid PTR on every sending IP for bulk mail.

Common mistakes

Assuming you can set the PTR in your own DNS
The reverse zone belongs to whoever owns the IP. You request the PTR from your hosting provider or ESP, not from the DNS panel where your A and TXT records live.
Leaving the default generic hostname
A PTR like 203-0-113-10.dynamic.isp.net reads as residential or dynamic space and hurts deliverability. Set a clean, dedicated mail hostname such as mail.example.com.
A PTR that does not match a forward record
If the hostname in your PTR does not resolve back to the same IP, forward-confirmed reverse DNS fails. Major providers now treat that as a reason to reject or spam-folder the mail.

Frequently asked questions

What is a PTR record used for?
A PTR record maps an IP address back to a hostname, which is the basis of a reverse DNS lookup. Mail servers use it to check that a connecting IP has a legitimate, matching hostname, a key anti-spam test. A missing or mismatched PTR is a common cause of mail being rejected or filtered.
How do I set a PTR record?
You usually cannot set it in your own DNS, because the reverse zone is controlled by whoever owns the IP address. Request it from your hosting provider, cloud platform, or email service, often through a control-panel field labelled “reverse DNS” or “PTR.”
What is the difference between a PTR record and an A record?
They are mirror images. An A record maps a hostname to an IP address (forward DNS), while a PTR record maps an IP address back to a hostname (reverse DNS). For mail servers the two should agree, which is what forward-confirmed reverse DNS verifies.
Reviewed by Jennifer Jackson, Email Deliverability Analyst · June 2026 ← Back to glossary