What Is a PTR Record?
A PTR (Pointer) record is a type of DNS record used for reverse DNS lookups. It maps an IP address back to a hostname — the opposite of an A record, which maps a hostname to an IP address.
How PTR Records Work
PTR records are stored in a special DNS zone called in-addr.arpa for IPv4 addresses (and ip6.arpa for IPv6). To perform a reverse DNS lookup, the IP address is reversed and appended to the arpa domain. For example, the PTR lookup for 203.0.113.25 queries 25.113.0.203.in-addr.arpa.
Why PTR Records Matter for Email
PTR records play a critical role in email deliverability. Many receiving mail servers perform a reverse DNS check on the sending server's IP address. If there is no PTR record, or if the PTR hostname does not resolve back to the same IP (called forward-confirmed reverse DNS or FCrDNS), the email may be rejected or marked as spam.
Google specifically requires valid PTR records for servers sending email to Gmail addresses. A properly configured PTR record signals that the IP address belongs to a legitimate, properly configured mail server.
Setting Up PTR Records
Unlike most DNS records, PTR records are managed by the owner of the IP address — typically your hosting provider or ISP. You need to contact them to set up a PTR record for your mail server's IP. The PTR should point to a hostname that resolves back to the same IP (forward-confirmed reverse DNS).
Frequently Asked Questions
What is reverse DNS (rDNS)?
Reverse DNS resolves an IP address back to a hostname, the opposite of a standard DNS lookup. It uses PTR records and is commonly used by mail servers to verify sending server identity.
Why do mail servers check PTR records?
Mail servers check PTR records as part of spam prevention. A server without a valid PTR record is often treated as suspicious, and many mail servers will reject or flag those emails.
How do I set up a PTR record?
Contact your hosting provider or ISP — they manage PTR records for their IP ranges. Request a PTR record pointing to your mail server's hostname, and ensure that hostname resolves back to the same IP.