IP Info
Parse and classify IPv4 and IPv6 addresses
An IP address is a number with structure. IPv4 packs 32 bits into four decimal octets; IPv6 uses 128 bits written as eight groups of hex, usually shortened by collapsing one run of zeros to a double colon. Beyond the arithmetic, large parts of both spaces are reserved — for private networks, loopback, documentation, multicast and link-local use.
Knowing which category an address falls into answers most practical questions immediately. An address starting 169.254 means DHCP failed; one in 10.0.0.0/8 will never be reachable from the internet; fe80:: is link-local and valid only on one segment. This tool parses and classifies without making any network request, so nothing about the address you check leaves the browser.
How to use it
- Paste an IPv4 or IPv6 addressThe version is detected automatically, including IPv6 addresses written in shortened or mixed notation.
- Read the classificationScope and category are shown — public, private, loopback, link-local, multicast, documentation or otherwise reserved.
- Compare notationsThe address is shown in its canonical and expanded forms, which is what you need when comparing IPv6 values that are written differently but are identical.
Frequently asked questions
Is this a geolocation lookup?
No, and deliberately not. Geolocation requires querying a third-party database, which would mean sending the address you are checking to someone else. This tool works purely from the structure of the address, so it can tell you an address is private or reserved but not where it is.
What does an address starting 169.254 mean?
It is link-local, self-assigned by the host because no DHCP server answered. On Windows it is called APIPA. The machine can talk to others on the same segment that did the same thing, and nothing else — so seeing one is almost always a sign that DHCP is broken.
What do the double colons in an IPv6 address mean?
They replace one run of consecutive zero groups, so 2001:db8:0:0:0:0:0:1 shortens to 2001:db8::1. Only one double colon may appear in an address, because two would make the number of omitted groups ambiguous. Leading zeros within a group are also dropped.
What is 127.0.0.1 and why is a whole block reserved for it?
It is loopback — traffic to it never leaves the machine. The entire 127.0.0.0/8 block is reserved, 16 million addresses for a job that needs one, which is a historical artefact of early classful allocation. IPv6 is more economical, reserving only ::1.
What are the documentation ranges for?
192.0.2.0/24, 198.51.100.0/24 and 203.0.113.0/24 for IPv4, and 2001:db8::/32 for IPv6, exist so that examples in books, articles and test fixtures cannot accidentally reference someone’s real host. Use them in documentation instead of inventing an address.