Network / IPv6
IPv6 Address Tools (Expand, Compress, Reverse DNS)
Expand or compress an IPv6 address, see what kind of address it is, find the IPv4 address inside it, its ip6.arpa reverse name, and the range of its prefix.
IPv6 Address Tools (Expand, Compress, Reverse DNS): The address is parsed in any valid notation, including embedded IPv4 and zone IDs such as %eth0, then written in full (eight groups of four hex digits) and in the compressed form RFC 5952 recommends: lower case, no leading zeros, and :: for the longest run of zero groups. Its type comes from the IANA special-purpose address registry, and the reverse name lists each hex digit backwards under ip6.arpa. Results were compared with Python's ipaddress module for 420 addresses. Runs 100% locally in your browser with zero server file uploads.
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| Compressed | 2001:db8::ff00:42:8329 | |
|---|---|---|
| Expanded | 2001:0db8:0000:0000:0000:ff00:0042:8329 | |
| Type | Documentation | |
| Reverse DNS name (PTR) | 9.2.3.8.2.4.0.0.0.0.f.f.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa | |
| Network | 2001:db8::/64 | |
| Range | 2001:db8:: – 2001:db8::ffff:ffff:ffff:ffff | |
| Addresses | 18,446,744,073,709,551,616 |
Compression follows RFC 5952, the form to use in logs and documentation; address types follow the IANA special-purpose address registry.
Reading an IPv6 address
The first half of a typical address, 64 bits, is the network prefix assigned by the provider and the network; the second half is the interface identifier, chosen by the device, often at random for privacy. Addresses starting fe80 are link-local and never leave the local network.
For IPv4 networks, the subnet calculator works out ranges and masks; to see your own public addresses, use what is my IP.
Addresses for examples
Use 2001:db8::/32 (or the newer 3fff::/20) in documentation and tests: they are reserved for examples and never routed on the internet, just as 192.0.2.0/24 is for IPv4.
How to use it
- Paste an IPv6 address in any valid form.
- Set a prefix length, such as 64 or 48, to see its network and range.
- Copy the compressed, expanded, or reverse DNS form you need.
Privacy & limitations
Everything is worked out in your browser; no lookups are made.
Related tools
Frequently asked questions
Why are there several ways to write one address?
Leading zeros in a group can be dropped, and one run of zero groups can be written ::, so 2001:0db8:0000:0000:0000:0000:0000:0001 and 2001:db8::1 are the same address. RFC 5952 picks one form so that addresses can be compared as text.
What prefix does a home network get?
Each network segment is normally a /64, and internet providers delegate a /48 or /56 to a home or office, enough for 65,536 or 256 segments.
What is the reverse DNS name for?
A PTR record at that name maps the address back to a host name, used by mail servers and logs. Delegated reverse zones end at a nibble boundary, such as a /48.
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