Reverse DNS Zones
Enter an IP or prefix — the matching in-addr.arpa or ip6.arpa zone, the PTR name and, where needed, the classless delegation per RFC 2317 follow immediately. Pairs with the DNS article.
Notes
- RFC 2317. For IPv4 prefixes between /25 and /31 there is no zone boundary of their own in reverse DNS. The calculator shows the usual classless delegation via a sub-zone and CNAME pointers.
- Nibble boundaries.
ip6.arpaworks in four-bit steps. Prefixes that do not fall on a nibble boundary are rounded up. - Runs in your browser. The calculation happens entirely on your device. Nothing you type is transmitted, stored or analysed.