IPv6 Reverse DNS (ip6.arpa) Generator
Turn any IPv6 address into its ip6.arpa reverse-DNS pointer name. The address is expanded to 32 hex nibbles, reversed, joined with dots and given the .ip6.arpa suffix — ready to drop into a PTR zone.
2001:db8::1 or fe80::1ff:fe23:4567:890a.
Reverse DNS answers the opposite question to normal DNS: instead of "what address does this name point to?", it asks "what name is behind this address?". The answer lives in a PTR record, and to look one up, resolvers need a special domain name derived from the IP address. For IPv6 that domain is ip6.arpa.
Building the name is mechanical. First the address is expanded to its full 128-bit form — eight groups of four hex digits, giving 32 hexadecimal nibbles in total. Those nibbles are then reversed (least-significant first), each becomes its own dot-separated label, and .ip6.arpa is appended. For 2001:db8::1 the result is a 32-label name ending in ...8.b.d.0.1.0.0.2.ip6.arpa.
IPv6 reverse DNS uses one label per 4-bit nibble, so a complete ip6.arpa name always has exactly 32 single-character labels. IPv4 works the same way but per octet, giving four labels under in-addr.arpa — see the IPv4 Reverse DNS generator for that.
This generator only constructs the name — it does not perform a lookup, and nothing you type leaves your browser. That makes it handy when you are authoring a reverse zone file or delegating a block, where you need the exact label sequence but do not want to publish anything yet. To learn how PTR records fit into the wider system, read reverse DNS and PTR records. If you would rather query the live PTR for an address, use the Reverse DNS Lookup tool, and to normalise an address first, the IPv6 Expand & Compress tool helps.
Frequently asked questions
What is an ip6.arpa reverse-DNS name?
The ip6.arpa name is the pointer (PTR) record name used to map an IPv6 address back to a hostname. It is built by expanding the address to 32 hexadecimal nibbles, reversing their order, separating each with a dot and appending .ip6.arpa.
Why are there 32 nibbles in an IPv6 PTR name?
An IPv6 address is 128 bits, or 32 hexadecimal digits (nibbles) of 4 bits each. Reverse DNS for IPv6 uses one label per nibble, so a full ip6.arpa name always has 32 single-character labels before the ip6.arpa suffix.
How do I create a PTR record for an IPv6 address?
Generate the ip6.arpa name here, then add a PTR record in the reverse zone that points that name to your hostname. Reverse DNS for IPv6 is delegated by your ISP or address holder, so you usually configure it in the zone they delegate to you.
Does this tool query DNS?
No. It only builds the ip6.arpa name from the address you type — the calculation runs entirely in your browser and no lookup is performed. If you want to look up the actual PTR record, use a reverse DNS lookup tool instead.
Want the theory? Read the guides → · Visit the zoo →