What does this test check?
Whether your network can use IPv6, and whether IPv6 slows you down. Your browser opens a few tiny test addresses, just as it opens any site:
IPv4-only and IPv6-only sites: whether each one works, and from which address.
A dual-stack site (it has both IPv4 and IPv6 addresses): which one your browser picks, and whether it sits waiting for IPv6 before falling back to IPv4.
Large IPv6 packets: a request big enough to need full-size packets, on a new connection. If the path's MTU is broken, small requests work but large ones vanish, and pages just keep loading.
Bare addresses with no name, one IPv6 and one IPv4: whether IPv6 works without DNS, and whether you're on an IPv6-only network with NAT64.
Each test asks two to four providers at once (Cloudflare, Google, DNSPod, AliDNS, icanhazip, ipify) and uses the first answer, so one provider being blocked or slow won't fail it.
How is the score worked out?
Out of 10, following test-ipv6.com's idea of how ready a network is for IPv6: 4 points if IPv6-only sites open, 2 if large IPv6 packets get through, 2 if dual-stack sites open without a wait, 1 if IPv6 works without DNS, and 1 if your browser picks IPv6. One point off if IPv6 takes more than 3 seconds to answer.
No IPv6 at all scores 0, but that doesn't mean anything is broken: every site still works over IPv4. A 10 means IPv6 works everywhere and slows nothing down.
I have no IPv6. How do I get it?
Most providers offer IPv6 now; often it's just switched off. In your router's admin page, find the IPv6 (or WAN → IPv6) settings and pick the mode your provider uses, usually DHCPv6 or "native", with prefix delegation turned on. Then make sure the local network hands out IPv6 addresses to your devices (SLAAC or DHCPv6).
If the router has no IPv6 setting, or your provider doesn't offer it, ask them. On a phone, mobile data usually has IPv6 even when your Wi-Fi doesn't.
Without IPv6, you're fine: every site works over IPv4. You only miss the few sites and apps that are IPv6 only.
IPv6 addresses work, but IPv6-only sites don't. Why?
Your IPv6 connection is fine, but your DNS isn't returning IPv6 addresses (AAAA records), so your browser never learns the site has one. Common causes: a router setting that filters AAAA records (some routers in China have it on by default), a DNS server that drops them, or a proxy app that handles DNS itself.
The fix: turn off AAAA filtering in the router, or switch to a public DNS such as 1.1.1.1, 8.8.8.8 or, in mainland China, 223.5.5.5.
What is the large-packet test (MTU)?
Data travels in packets of up to about 1,500 bytes (that limit is the MTU). On some IPv6 paths (tunnels, PPPoE, misconfigured routers), full-size packets are too big for one link, and the message asking the sender to "send smaller ones" gets blocked. Small requests work, so the connection looks fine, but large pages, images and downloads hang.
The test sends a 3.5 KB request to an IPv6-only host on a new connection, which needs full-size packets both ways. If it fails while the small IPv6 test passes, lower the MTU in your router's IPv6 or WAN settings (try 1,480 or 1,452 on PPPoE), or ask your provider.
Why does my browser pick IPv4 when IPv6 works?
It's not a fault, and IPv6-only sites still open. Browsers try both and use whichever connects first (this is called Happy Eyeballs). If IPv4 wins, IPv6 connects more slowly on your network, or your system prefers IPv4: Windows does this for tunnelled IPv6 (6to4, Teredo), and many proxies and VPN apps carry only IPv4.
I use a proxy or VPN. Whose result is this?
Mostly the proxy's. With a proxy on, the test sites are reached through it, so the addresses and IPv6 support you see are the proxy server's. A proxy that carries only IPv4 makes it look as if you have no IPv6. To test your own network, turn the proxy off (or let these hosts connect directly) and test again.
What is an IPv6-only network with NAT64?
A normal setup that works with almost every app, so there's nothing to do. Some mobile networks give phones IPv6 only. So that IPv4-only sites still open, the provider's DNS makes up an IPv6 address for them (DNS64), and a gateway translates it to IPv4 (NAT64). Sites open by name, but an IPv4 address typed in directly can't be reached, and that's how the test spots it.
Do you collect my data?
This site never receives your results. The tests go straight from your browser to the test hosts (Cloudflare, Google and others), which see your IP address like any site you visit. Your results go into a link only when you share: it holds the test results and times, your country only if you tick the box, and never your IP address. The code is open source on GitHub.
What does the IPv4 vs IPv6 comparison show?
Four networks (Cloudflare, Google, Akamai and DNSPod) each have one way in over IPv4 only and one over IPv6 only. The test asks both at the same time and measures latency on the open connection (the lowest of three tries), so the difference reflects the path your provider gives each protocol, not the server. The headline is the median difference across the networks that answered both ways; within 10 ms (or 15%) they count as equally fast.
It doesn't affect your score: a slightly slower IPv6 still works. Google doesn't answer in mainland China, and DNSPod's servers are there: from elsewhere both its times are long, and its difference shows the route to China.
