Reverse DNS PTR Generator

Generate reverse DNS pointer names

Reverse DNS maps an IP address back to a hostname using a specially formatted pointer name. For IPv4 the four octets are reversed and the suffix in-addr.arpa is appended, so 8.8.4.4 becomes 4.4.8.8.in-addr.arpa. For IPv6 the address is fully expanded to thirty-two hex digits, each digit is reversed and separated by dots, and ip6.arpa is appended. This generator produces the correct pointer name for either protocol and shows a sample PTR record line for IPv4.

Getting the order and expansion right by hand is fiddly, especially for IPv6, so an automated generator removes a common source of zone-file errors.

Why reverse DNS matters

Mail servers frequently check that a sending IP has a matching reverse DNS record, and a missing or mismatched PTR record is a common reason legitimate email is marked as spam. Reverse DNS also helps with logging, troubleshooting and security investigations, where turning an address back into a name makes records far more readable.

The PTR record itself lives in the reverse zone and is usually managed by whoever controls the IP block, such as a hosting provider. This tool builds the pointer name you need to request or configure. All generation happens locally in your browser.

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