IPv6 Reverse DNS Name Generator
Generate nibble-format reverse lookup names.
IPv6 Reverse DNS Name Generator: inputs and results
Enter an IP address, CIDR prefix, or range. Then check its first and last address below.
Calculated Boundaries & ParametersReady
Key Capabilities
- •100% Client-Side: Zero telemetry or server latency.
- •RFC Compliant: Exact 32-bit and 128-bit integer precision.
- •Quick Copy: Instant access to CIDR, mask, and range bounds.
- •Cross-Platform: Works on desktop, tablet, and mobile browsers.
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How IPv6 Reverse DNS Name Generator Works?
This tool works by expanding the address to 32 hex digits, reversing the digit order, separating each digit with a dot, and appending ip6.arpa.
Enter an IPv6 address
Type an address such as
2001:db8::567:89ab.Expand to 32 nibbles
The generator writes all 32 hex digits with no colons.
Reverse the nibbles
The last digit becomes the first label.
Append the suffix
The generator joins the 32 digits with dots and adds
.ip6.arpa, giving a 72-character name.
IPv6 Reverse DNS Name Generator Formula
The formula is PTR Name = n₃₂.n₃₁.….n₁.ip6.arpa, where n₁ to n₃₂ are the 32 nibbles of the expanded address.
Nibble count
128 bits ÷ 4 = 32 nibblesEach nibble is 1 hex digit.
Label order
reverse(nibbles)RFC 3596 nibble format.
Zone for prefix p
first p ÷ 4 nibbles reversed + .ip6.arpaWorks for nibble-aligned prefixes.
Name length
32 × 2 + 8 = 72 charactersWithout a trailing dot.
Worked example: 2001:db8::567:89ab
Expanded = 2001:0db8:0000:0000:0000:0000:0567:89ab PTR = b.a.9.8.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa Zone /32 = 8.b.d.0.1.0.0.2.ip6.arpa
IPv6 Reverse DNS Name Generator Conversion Table
The table shows the ip6.arpa PTR name for 6 IPv6 addresses.
| IPv6 Address | PTR Name |
|---|---|
| ::1 | 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa |
| 2001:db8::1 | 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa |
| 2001:db8::567:89ab | b.a.9.8.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa |
| 2001:db8:acad:10::25 | 5.2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.0.d.a.c.a.8.b.d.0.1.0.0.2.ip6.arpa |
| fd00:1:2:3::a | a.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.3.0.0.0.2.0.0.0.1.0.0.0.0.0.d.f.ip6.arpa |
| 2606:4700::1111 | 1.1.1.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.7.4.6.0.6.2.ip6.arpa |
What is IPv6 Reverse DNS Name Generator?
The IPv6 Reverse DNS Name Generator is a tool that builds the ip6.arpa domain name used for reverse DNS (PTR) lookups of an IPv6 address.
Reverse DNS maps an address back to a hostname. RFC 3596 defines the IPv6 format: every one of the 32 hex digits becomes its own DNS label, in reverse order. Typing a 72-character name by hand invites errors, and a single wrong nibble breaks the lookup.
Mail servers, logging systems, and security tools rely on reverse DNS. Many receiving mail servers reject messages from IPv6 hosts without a matching PTR record.
What are the uses of IPv6 Reverse DNS Name Generator?
There are 4 main uses of the IPv6 Reverse DNS Name Generator, including PTR record creation, mail delivery, and zone delegation.
Creating PTR records
DNS zone files need the full nibble name for each host record.
Fixing mail deliverability
Mail servers on IPv6 need a PTR record that matches the forward hostname.
Delegating reverse zones
ISPs delegate a /48 or /56 reverse zone to customers using the nibble zone name.
Querying reverse DNS manually
The name works directly in
dig PTRqueries.