These hosts have no A (IPv4) record — they exist only on IPv6. If your device can reach them, your IPv6 routing to the internet is fully operational.
These servers have both A and AAAA records. They serve as connectivity and latency benchmarks.
Measures TCP round-trip time between your device and the Kubernetes cluster in Oracle Cloud (São Paulo).
Structured diagnostic output. Use this when contacting your ISP's network operations or Level 2 support team.
IPv6 is the sixth version of the Internet Protocol, designed to replace IPv4. While IPv4 supports ~4.3 billion unique addresses, IPv6 provides 340 undecillion (3.4×10³⁸) addresses — effectively eliminating address exhaustion. IPv6 uses 128-bit addresses written in hexadecimal groups separated by colons, such as 2001:db8::1.
IPv6 enables true end-to-end connectivity — your device gets a real, globally routable address without address translation. This improves performance for real-time apps (gaming, VoIP, video calls), enables peer-to-peer connections, and eliminates the complexity and failures introduced by NAT layers between you and the internet.
Dual-stack means your device and network support both IPv4 and IPv6 simultaneously. When you connect to a dual-stack website, your operating system uses the "Happy Eyeballs" algorithm (RFC 8305) to race both protocols and choose the fastest one — typically IPv6 when available, falling back to IPv4 if IPv6 is slower or broken.
Carrier-Grade NAT (CGNAT) is when your ISP places many customers behind a single shared IPv4 address. You get a private IP from your router, which is then NATted again by the ISP. CGNAT breaks inbound connections, causes issues with VPNs, gaming, and VoIP, and makes it impossible to host any service. IPv6 eliminates the need for CGNAT entirely.
Your score out of 10 aggregates all tests: IPv6 connectivity (3pts), IPv6-only probe reachability (3pts), DNS AAAA resolution (2pts), privacy extensions (1pt), and latency quality (1pt). A score of 10/10 means your connection is fully IPv6-ready. Below 7 typically indicates your ISP has not fully deployed IPv6 or has routing issues.
For a browser to use IPv6, it must first resolve a domain name to an AAAA record. This test verifies that your DNS resolver can handle AAAA queries. If this test fails but you have an IPv6 address, your DNS resolver may be filtering or not returning AAAA records — this can be fixed by switching to a public IPv6-capable resolver like 2606:4700:4700::1111 (Cloudflare).
IPv6 requires a minimum MTU of 1280 bytes and relies on Path MTU Discovery (PMTUD) to negotiate the optimal packet size end-to-end. If a firewall drops ICMPv6 "Packet Too Big" messages, large transfers silently stall — a common cause of partial IPv6 breakage where small requests work but large ones hang. Our MTU test sends a >1500 byte response to detect this.
Modern operating systems and browsers implement the Happy Eyeballs algorithm to avoid waiting for a slow IPv6 connection before trying IPv4. It races both protocol connection attempts and uses whichever responds first. Our test measures whether your browser prefers IPv6 on dual-stack hosts by comparing response times to an IPv6-only endpoint vs. a dual-stack endpoint.