Glossary / PTR record (reverse DNS)

PTR record (reverse DNS)

A PTR record (pointer, reverse DNS) does the opposite of an A record: it turns an IP address back into a hostname. So 185.91.72.34 resolves to mail.example.com. PTR matters most to mail servers, so their messages are treated as genuine.

Regular DNS answers "what is the IP for this domain," while reverse DNS answers the opposite: "what is the name for this IP." PTR records live in a separate zone (in-addr.arpa for IPv4) and are controlled not by the domain owner but by whoever owns the IP - usually the host or ISP.

Their main use is email. Many mail servers check whether the sender's IP has a valid PTR and whether it matches the server's name (forward and reverse resolution). If PTR is missing or random, the message easily lands in spam or gets rejected.

That is why PTR is almost always set by the host or server owner, not by you in the domain panel. For a site on shared hosting it is usually already handled by the provider; the question comes up with a dedicated IP or your own mail server.

Example

34.72.91.185.in-addr.arpa.  3600  IN  PTR  mail.example.com.

Common mistakes

• Trying to add PTR in your own domain's zone; it actually lives in the IP's zone and is set by the IP owner.
• Thinking every site needs PTR; it is critical mainly for mail servers.
• Leaving a PTR that does not match the server's name, so mail loses trust despite the record existing.
• Confusing forward and reverse DNS: A takes a name to an IP, PTR takes an IP back to a name.

Related terms

• A record A record (DNS address record)
• AAAA record AAAA record (DNS IPv6 record)
• CNAME record CNAME record (DNS alias)
• MX record MX record (mail exchanger)
• TXT record TXT record (DNS text record)