What Is IPv6? Address Format, Types and How to Check

IPv6 is the newer version of the Internet Protocol. Its addresses are 128 bits long and written as groups of hexadecimal digits, such as 2001:db8:85a3::8a2e:370:7334, which gives enough addresses for every device to have its own. Most networks now run IPv6 alongside the older IPv4. Our IP checker shows your IPv6 address on the line under your main IP if your connection has one.

Why was IPv6 created?

IPv4 addresses are 32 bits, which allows about 4.3 billion of them, and that is not enough for every phone, computer and device online. IPv4 networks cope by sharing addresses through NAT and carrier-grade NAT. IPv6 uses 128-bit addresses, as defined in RFC 4291, so the address space is 2 to the power 128: large enough that address shortage is no longer the limit. The protocol itself is specified in RFC 8200.

What does an IPv6 address look like?

An IPv6 address is eight groups of four hexadecimal digits separated by colons. RFC 5952 sets the rules for writing it short:

Leading zeros in each group are dropped, so 0db8 becomes db8.
The longest run of all-zero groups is replaced once by ::, but never a single zero group.
Letters are written in lowercase.

Full form	Short form
2001:0db8:0000:0000:0000:0000:0002:0001	2001:db8::2:1
0000:0000:0000:0000:0000:0000:0000:0001	::1

The first part of an address (usually the first 64 bits) is the network prefix your provider gives you, and the rest identifies the device. Prefixes are written in CIDR notation, such as 2001:db8::/32; our subnet calculator works them out.

Types of IPv6 addresses

Type	Looks like	Used for
Global unicast	Your public address, from your provider's prefix	Talking to the internet
Link-local	fe80::/10	The local network only; every interface has one
Loopback	::1	The device talking to itself, like 127.0.0.1
Multicast	ff00::/8	Sending to a group of devices at once

RFC 4291 requires every interface to have a link-local address and says routers must not forward packets with link-local source or destination addresses. Seeing an fe80 address next to a working connection is normal, as our guide to 169.254 and link-local addresses explains.

Why does my device have several IPv6 addresses?

A typical phone or laptop has a link-local address, a stable global address and one or more temporary addresses. Temporary addresses are a privacy feature defined in RFC 8981: the device generates a random address and switches to a new one over time, so websites cannot follow it by a fixed address. RFC 8981 sets the default preferred lifetime of a temporary address at one day.

IPv6 and NAT

IPv6 normally works without NAT. Each device gets a public address, and your router's firewall decides which incoming connections are allowed. That makes hosting and peer-to-peer connections simpler, and it means port forwarding is replaced by firewall rules. Keep the router firewall on.

How to check if you have IPv6

Open the ipcomet home page. If the IPv6 line shows an address, your connection supports IPv6; "Not detected" means it does not.
On Windows, run ipconfig and look for an IPv6 address that does not start with fe80. On a Mac or Linux, run ifconfig or ip -6 addr.
If you use a VPN, check that your real IPv6 address does not show up, using our guide to testing a VPN.

For how the two versions compare side by side, read IPv4 vs IPv6.

Frequently asked questions

Is IPv6 better than IPv4?

It solves the address shortage and removes the need for NAT, which simplifies many things. Speed depends on the network path more than the protocol version, so most people will not notice a difference in everyday browsing.

Should I turn off IPv6?

Usually not. Modern systems prefer IPv6 when it works and fall back to IPv4 when it does not. Turning it off can break some services and rarely fixes anything. If a VPN leaks your IPv6 address, use a VPN that handles IPv6 instead.

Can websites see my IPv6 address?

Yes, when you connect over IPv6 that address is what the website sees, just as with IPv4. Temporary addresses limit how long one address follows you.

What is my IPv6 address?

Our IP checker shows it under your main address. Your device may also list a link-local fe80 address, which is local only and not what websites see.

Sources and further reading

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