What is IPv6 and why does it matter?

IPv6 is the newer version of the internet protocol with a practically unlimited supply of addresses. IPv4 addresses ran out years ago, so ISPs share one address between many customers; with IPv6 every device gets its own, and connections go direct, without NAT.

Why don’t I have IPv6?

Most likely your ISP hasn’t enabled it on your line, or your router has it switched off. That’s common and nothing is broken: the whole web still works over IPv4. If you want IPv6, ask your ISP or check the router settings.

IPv6 works, but the browser picks IPv4 — is that bad?

Browsers race both protocols and keep whichever connects faster (Happy Eyeballs). If IPv4 wins consistently, IPv6 on your line is slower or flaky: it works, but you don’t benefit from it.

What are 6to4 and Teredo tunnels?

Ways to get IPv6 over an IPv4-only line: addresses starting with 2002: (6to4) or 2001:0: (Teredo). They are slow and unreliable, and your ISP has no native IPv6. If you see one, it’s usually better to turn the tunnel off.

My resolver can’t reach IPv6-only name servers — is that a problem?

Rarely, today: almost every domain has name servers reachable over IPv4 too. But such a resolver is a sign your ISP’s DNS isn’t ready for IPv6, and the few IPv6-only domains won’t open for you.

IPv6 and VPN: can my real address leak?

Yes. Many VPNs tunnel only IPv4; if your line has IPv6, sites still see your real IPv6 address and your ISP. Check it on the main page — the IPv6 card shows which address sites see — and run the DNS leak test as well.

← My IP

IPv6 connectivity

IPv6 test

Six quick probes from your browser show whether you have IPv6, what your address is and who it belongs to, whether the browser prefers IPv6 over IPv4, whether large packets get through and whether your ISP’s resolver reaches IPv6-only name servers. No IPv6 is not a fault — many ISPs simply haven’t enabled it yet.

Your IPv4 —

Your IPv6 —

starting the test…

—/ 10

The test hasn’t run yet.

Test	Result	Details
IPv4 only	not checked yet	—
IPv6 only	not checked yet	—
Dual stack	not checked yet	—
Large response over IPv6	not checked yet	—
Large response over IPv4	not checked yet	—
Resolver over IPv6	not checked yet	—

What the test checks

IPv4 only: A host that has only an A record: does plain IPv4 work, and what is your IPv4 address.
IPv6 only: A host with only an AAAA record: if it answers, your IPv6 works, and its reply is your IPv6 address.
Dual stack: A request to a host with both records shows which protocol your browser actually prefers.
Large response: A reply longer than 1500 bytes: if it gets lost over IPv6, big packets don’t fit the path (an MTU problem) and some sites will stall.
Resolver over IPv6: Can your ISP’s DNS resolver query name servers that have IPv6 addresses only.
Addresses: The provider and country of each address, plus 6to4 and Teredo tunnels, which mean the IPv6 isn’t native.

What the states mean

works: The probe went through: the connection over this protocol works, and the browser or resolver behaves as expected.
attention: The probe failed or the result needs attention: no connection over this protocol, IPv4 preferred over working IPv6, large packets lost, a resolver without IPv6. What exactly — in the details.
skipped: The probe was skipped: the host isn’t set up, or it depends on another probe that failed. Skipped probes don’t count toward the score, and the maximum shrinks accordingly.

IPv6 questions

What is IPv6 and why does it matter?: IPv6 is the newer version of the internet protocol with a practically unlimited supply of addresses. IPv4 addresses ran out years ago, so ISPs share one address between many customers; with IPv6 every device gets its own, and connections go direct, without NAT.
Why don’t I have IPv6?: Most likely your ISP hasn’t enabled it on your line, or your router has it switched off. That’s common and nothing is broken: the whole web still works over IPv4. If you want IPv6, ask your ISP or check the router settings.
IPv6 works, but the browser picks IPv4 — is that bad?: Browsers race both protocols and keep whichever connects faster (Happy Eyeballs). If IPv4 wins consistently, IPv6 on your line is slower or flaky: it works, but you don’t benefit from it.
What are 6to4 and Teredo tunnels?: Ways to get IPv6 over an IPv4-only line: addresses starting with 2002: (6to4) or 2001:0: (Teredo). They are slow and unreliable, and your ISP has no native IPv6. If you see one, it’s usually better to turn the tunnel off.
My resolver can’t reach IPv6-only name servers — is that a problem?: Rarely, today: almost every domain has name servers reachable over IPv4 too. But such a resolver is a sign your ISP’s DNS isn’t ready for IPv6, and the few IPv6-only domains won’t open for you.
IPv6 and VPN: can my real address leak?: Yes. Many VPNs tunnel only IPv4; if your line has IPv6, sites still see your real IPv6 address and your ISP. Check it on the main page — the IPv6 card shows which address sites see — and run the DNS leak test as well.
Score: Working IPv6 — 5 points; the browser prefers IPv6 on a dual-stack host — +2; a large response over IPv6 gets through — +2; the resolver reaches IPv6-only name servers — +1. Skipped probes don’t count and lower the maximum. No IPv6 — 0 of 10.