IPv4 vs IPv6
IPv4 has been the internet’s addressing scheme since 1981. IPv6 was standardised in 1998 to replace it. Nearly three decades later both are still running, side by side, and most connections carry whichever the two ends agree on.
The essential difference is size
| IPv4 | IPv6 | |
|---|---|---|
| Length | 32 bits | 128 bits |
| Written as | 203.0.113.42 | 2001:db8::8a2e:370:7334 |
| Total addresses | ~4.3 billion | ~340 undecillion |
| Standardised | 1981 | 1998 |
| Address configuration | Usually DHCP | Usually autoconfiguration |
Four point three billion sounded limitless when the world had a few thousand connected machines. It stopped being enough around 2011, when the central pool ran dry. IPv6 does not merely add addresses; it adds so many that the shortage cannot recur.
What running out actually caused
Rather than switch, the internet worked around exhaustion — and the workarounds are why IPv4 still feels normal.
NAT lets one public address serve a whole household. Carrier-grade NAT goes further, putting hundreds or thousands of subscribers behind one address. It works, but it breaks things that assume an address means one customer: inbound connections, some gaming and peer-to-peer setups, and abuse handling, since one bad actor can get an entire block of neighbours blocked.
IPv6 removes the need for this. Every device can hold a globally routable address of its own.
What changes for you
Very little, deliberately. Your browser prefers IPv6 when both ends support it and falls back silently when they do not. Two practical effects are worth knowing:
- Your IPv6 address changes more often than you would expect. Privacy extensions rotate the device-specific half regularly, so it cannot serve as a permanent identifier.
- Address-based blocking works differently. Because a household holds a whole IPv6 range rather than a single address, services that block by address typically block the range.
Which one are you using?
Look at the address at the top of the home page. Dots mean IPv4; colons mean IPv6. Many connections have both and will show whichever was used to reach this page.
Frequently asked questions
Is IPv6 faster than IPv4?
Not inherently, though it often is in practice. IPv6 usually avoids carrier-grade NAT, which removes a translation step and a shared bottleneck. The difference is small and depends entirely on the route.
Do I need to do anything to use IPv6?
No. If your provider offers it, your devices use it automatically and prefer it when both ends support it.
Why does my IPv6 address change so often?
By design. Privacy extensions rotate the part of the address derived from your device, so it cannot be used as a long-term identifier. The network half stays stable.
Can IPv4 and IPv6 talk to each other directly?
No. They are separate protocols. Reaching across requires a translation or tunnelling mechanism, which is why providers run both at once instead of switching over.