There are two versions of the Internet Protocol in use: IPv4 and IPv6. Both do the same job — identifying devices on a network — but they look very different and exist for different reasons.
Why IPv6 was created
IPv4 uses 32-bit addresses, which allows for about 4.3 billion unique addresses. That sounded like plenty in the 1980s, but with billions of phones, computers and smart devices online, the world simply ran out. IPv6 uses 128-bit addresses, providing about 340 undecillion — effectively unlimited.
How the formats compare
| IPv4 | IPv6 | |
|---|---|---|
| Example | 203.0.113.42 | 2001:db8::8a2e:370:7334 |
| Length | 32-bit | 128-bit |
| Format | Four numbers (0–255), dots | Eight groups of hex, colons |
| Total addresses | ~4.3 billion | ~340 undecillion |
Do they work together?
IPv4 and IPv6 aren't directly compatible, so most of the internet runs both at once (called "dual stack"). Your device usually has both an IPv4 and an IPv6 address, and it uses whichever the destination supports.
Which one am I using?
Most likely both. Our home page shows your IPv4 and IPv6 addresses side by side — if the IPv6 line is filled in, your connection supports it. For more detail on any address, try the IP lookup tool. New to the basics? Start with what is an IP address.