IPv6 Reverse DNS Generator
Keep the IPv6 host intact while generating its PTR owner, zone and BIND fragment
The PTR owner preserves the original host; the prefix selects the zone. /0 uses ip6.arpa. Only prefixes divisible by 4 are supported. Replace the host.example. placeholder. No DNS lookup or publication occurs.
About this tool
IPv6 Reverse DNS Generator reverses the original host address into 32 hexadecimal labels for its absolute PTR owner. When a CIDR is supplied, only the containing zone uses the prefix: 2001:db8:1234::53/64 still generates the owner for ::53, not the network address. Prefix /0 produces ip6.arpa.; a bare address uses /128. This interface generates one direct zone for prefixes divisible by four. Other prefixes need a separate delegation design, rather than being inherently impossible in reverse DNS. The BIND fragment uses $ORIGIN and a relative owner with host.example. as a target placeholder. It is not a complete zone file and does not verify delegation, resolve a hostname or publish DNS.
Production Snippets
The allocation prefix must not replace the PTR host
text
Input: 2001:db8:1234::53/64
Normalized host: 2001:db8:1234::53
Zone: 0.0.0.0.4.3.2.1.8.b.d.0.1.0.0.2.ip6.arpa.
$ORIGIN 0.0.0.0.4.3.2.1.8.b.d.0.1.0.0.2.ip6.arpa.
3.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0 IN PTR host.example.
Replace host.example. with the intended absolute hostname.
This fragment does not provide SOA, NS or delegation.Frequently Asked Questions
Does a CIDR input lose the original host bits?
No. The PTR owner uses all 128 bits of the supplied host. Only the reverse zone is selected by the prefix; /64 does not turn an address ending in ::53 into ::.
What are the /0 and /128 cases?
At /0 the zone is ip6.arpa. without a leading dot, and the relative owner has 32 labels. At /128 the zone equals the absolute PTR owner and the record uses @.
Why does the tool require a prefix divisible by four?
It produces one direct zone whose labels each represent four bits. Nonaligned allocations may require multiple zones or another delegation arrangement, which this generator does not plan.
What should replace host.example.?
Use the intended absolute target hostname, including its final dot. The example is a placeholder, not a resolved hostname or a name derived from the IPv6 address.
Is the copied BIND output a complete zone?
No. It is an $ORIGIN directive and a PTR record fragment. SOA, NS, delegation, TTL policy and existing zone contents remain part of your DNS configuration.
Which address syntax is accepted?
IPv6 compressed, expanded and embedded-IPv4 forms are accepted, with optional paired brackets. IPv4-only addresses, zone suffixes and malformed or empty prefixes are rejected. Inputs are processed locally and limited to 256 bytes.
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