2026-09-15 · IPV4 Scanner
IPv6 has been finished since 1998. Nearly thirty years later a large part of the internet still runs on IPv4, and most people only notice the difference when something shows them an address full of colons and they wonder what broke.
Nothing broke. Here is what changed, why it took so long, and what it means for you.
An IPv4 address is 32 bits, which allows about 4.3 billion unique values. In 1981 that was an absurd surplus. There were a few hundred computers on the network and the idea that the supply could run out was not worth planning around.
Then everyone got a computer, then a phone, then a second phone, then a thermostat. The regional registries began running out of fresh blocks in 2011, and today new IPv4 addresses are essentially traded rather than allocated — they have a market price.
IPv6 uses 128 bits. The number of addresses that produces is genuinely difficult to convey: it is roughly 340 undecillion, a 39-digit number. Every grain of sand on earth could have billions of addresses. The supply problem is solved permanently rather than postponed.
Address length is the headline, but it is not the only change.
No more NAT by necessity. IPv4 survived its own shortage through Network Address Translation: your whole household hides behind one public address. It works, but it broke the original model where any device could address any other, which is why peer-to-peer applications, game hosting and video calls all need workarounds. With IPv6 every device can have its own public address, and the workarounds become unnecessary.
Simpler headers. The IPv6 packet header is fixed-length with fewer fields, which makes it cheaper for routers to process. Fragmentation is handled by the sender rather than by routers along the way.
Autoconfiguration built in. An IPv6 device can construct a working address by listening to the local router, without a DHCP server at all.
No broadcast. IPv6 replaces broadcast traffic with multicast, so devices are not interrupted by messages that were never meant for them.
Because the two protocols do not interoperate. An IPv6-only host cannot talk to an IPv4-only host directly. There is no flag day, and no way to upgrade half the internet and have it still work.
So the transition runs on dual stack: devices and networks run both at once, using IPv6 where both ends support it and falling back to IPv4 otherwise. That works, but it means the cost of adoption is paid before any benefit arrives — you run two networks, debug two sets of problems, and everything still has to work for IPv4 users regardless. That economics, rather than any technical obstacle, is why it took decades.
Meanwhile NAT kept IPv4 usable enough. A solution that is merely adequate and already deployed is a formidable competitor.
They look worse than they are. An address is eight groups of four hexadecimal digits separated by colons:
2001:0db8:0000:0000:0000:ff00:0042:8329Two rules shorten it. Leading zeros in a group can be dropped, and one run of all-zero groups can be replaced with a double colon. So the above is normally written:
2001:db8::ff00:42:8329The double colon may appear only once, because more than one would make the length ambiguous. A few prefixes are worth recognising: fe80:: is link-local, valid only on the local segment; ::1 is loopback, the IPv6 equivalent of 127.0.0.1; and 2001:db8:: is reserved for documentation, which is why it appears in every example including this one.
For most people, nothing you need to act on. Your connection probably already has IPv6, your operating system prefers it when available, and you would not know unless you looked — the IP lookup tool will show you which one you are currently being seen on.
Two things are worth knowing. First, an IPv6 address can be more identifying than an IPv4 one: instead of sharing a household address, your device may have its own. Privacy extensions, which rotate the address regularly, exist for exactly this reason and are on by default in current operating systems.
Second, if you run anything — a server, a firewall, an access control list — check whether your rules cover IPv6 as well. A firewall carefully configured for IPv4 that ignores IPv6 entirely has an open door beside a locked one. This is a genuinely common and serious oversight.
Do I need to do anything to use IPv6?
Almost certainly not. If your provider offers it, your router and devices negotiate it automatically and prefer it where both ends support it.
Is IPv6 faster than IPv4?
Not inherently, though it can be in practice because it avoids carrier-grade NAT, which adds a translation step and can add latency. The difference is usually small.
Will IPv4 be switched off?
Not on any timetable worth planning around. It will fade over decades as the cost of maintaining it exceeds the cost of dropping it. Plenty of networks will run both for a very long time.
Why does a site show me an IPv6 address when I expected IPv4?
Because your connection supports both and your device preferred IPv6, as it is designed to. Nothing is wrong.
Is IPv6 more secure?
Only marginally, and not in the way people assume. IPsec support was made mandatory in the original specification but is not mandatory in use. The bigger practical risk is a firewall configured for IPv4 that silently permits everything over IPv6.