The internet runs on two versions of the Internet Protocol side by side: the original IPv4, introduced in the early 1980s, and its successor IPv6. Most people never need to think about which one they use, but understanding the difference helps when troubleshooting, gaming or running servers.
The address shortage
IPv4 addresses are 32 bits long and written as four numbers from 0 to 255, such as 198.51.100.24. That allows roughly 4.3 billion unique addresses – far fewer than the number of phones, computers and connected devices in use today. The regional registries that hand out addresses ran out of new IPv4 blocks during the 2010s.
Providers stretched the supply with NAT, letting many devices share one address. It works, but it adds complexity, can break some games and peer-to-peer apps, and makes hosting from home harder.
How IPv6 is different
IPv6 addresses are 128 bits long, written as eight groups of hexadecimal digits separated by colons, for example 2001:db8:85a3::8a2e:370:7334. A double colon (::) replaces one run of zero groups to keep addresses shorter. The number of possible addresses is so large – about 340 undecillion – that every device can have its own globally unique address.
| IPv4 | IPv6 | |
|---|---|---|
| Address length | 32 bits | 128 bits |
| Example | 203.0.113.5 | 2001:db8::5 |
| Total addresses | ~4.3 billion | ~3.4 × 1038 |
| Needs NAT at home | Usually | No |
| Typical home allocation | 1 public address | A whole subnet (/64 or larger) |
Do I have IPv6?
Run our IPv6 test. It tries to reach separate IPv4-only and IPv6-only servers and tells you which work. Many mobile networks and fibre providers now enable IPv6 by default; others still offer IPv4 only.
Is IPv6 faster or safer?
Neither protocol is inherently faster. IPv6 can be slightly quicker where it avoids carrier-grade NAT, and slightly slower if your provider's IPv6 routing is less mature. For privacy, modern devices use temporary IPv6 addresses that rotate regularly. Your router's firewall still protects devices on IPv6 – check that it is enabled.
What should I do?
Usually nothing: browsers automatically use whichever protocol works best (a technique called “Happy Eyeballs”). If you host services, play online games or want to future-proof your network, enable IPv6 in your router settings if your ISP supports it.