Network
IPv6 Readiness Test
Test a domain over IPv6
We'll test the website, DNS and email of this domain over IPv6
Try:
google.com
cloudflare.com
github.com
Tool features
6 checks
Real IPv6 connections
Opens HTTPS, HTTP, DNS and SMTP connections over IPv6 — not just a check that an AAAA record exists.
IPv4 / IPv6 parity
Compares the response over both protocols, so a site that answers differently on IPv6 stands out.
Certificate over IPv6
Validates the TLS certificate on the IPv6 address, catching listeners set up with the wrong certificate.
Nameserver reachability
Checks each nameserver has an IPv6 address and really answers queries on it.
Mail over IPv6
Reads the SMTP greeting over IPv6 and checks the reverse DNS that Gmail requires for IPv6 mail.
Scored, with fixes
An A–F grade, a verdict per area and the specific change that fixes each failing check.
What IPv6 readiness means & how it's tested
A domain is IPv6-ready when people on IPv6-only networks can use all of it: load the website, resolve its DNS and deliver its email. Most mobile carriers and many ISPs now hand out IPv6 first, and a growing number of networks are IPv6-only behind NAT64.
An AAAA record alone isn’t enough. If the server doesn’t listen on IPv6, its firewall drops IPv6 traffic, or the IPv6 listener serves the wrong certificate, visitors see slow fallbacks or errors that never show up when you test over IPv4. This test connects over IPv6 the same way a visitor, resolver or mail server would.
AAAA record
The DNS record that maps a name to an IPv6 address (A is the IPv4 equivalent).
Dual-stack
Serving the same site over both IPv4 and IPv6, so every visitor gets a native path.
FCrDNS
Forward-confirmed reverse DNS: the IPv6 address has a PTR name that resolves back to it.
How to use this tool
1
Enter a domain
Type a domain such as
example.com — a URL or email address works too.2
Run the test
We connect to the website, nameservers and mail servers over IPv6, and compare the site with its IPv4 answer.
3
Read the verdict
See the overall grade and whether the website, DNS and email each work over IPv6.
4
Apply the fixes
Each failing check comes with the specific change to make, from adding an AAAA record to opening the IPv6 firewall.
Related tools
8 tools
DNS Lookup
Perform DNS queries for A, AAAA, MX, TXT, CNAME, and other DNS record types
Nameserver Health Check
Check your domain's own nameservers for responsiveness, DNSSEC status, and latency
HTTP/3 Test
Check if H3/QUIC is enabled on your website. Test HTTP/3 support and analyze Alt-Svc headers
Port Checker
Check if specific ports are open on a server or IP address with connection testing
SMTP Test
Test an SMTP server end to end with a timed connection trace covering TLS, login and recipient acceptance, and optionally send a test email
PTR Lookup
Perform reverse DNS lookup to find hostname from IP address (PTR records)
Domain Health Checker
Full domain audit report covering DNS, DNSSEC, WHOIS, SSL/TLS, security headers, CDN, IPv6, HTTP/2 & HTTP/3, blacklists, DNS propagation and email authentication
Online Ping
Ping servers to check connectivity and measure response time with detailed statistics
IPv6 Readiness Test — Frequently Asked Questions
6 Q&A
No. The AAAA record only publishes an address. The web server also has to listen on IPv6, the firewall has to allow it, and the IPv6 listener has to serve the same certificate and site as IPv4. A broken AAAA record is worse than none, because IPv6 visitors try it first and wait for a timeout.
Your own network is probably reaching the site over IPv4. Browsers fall back from IPv6 to IPv4 quickly (Happy Eyeballs), so a broken IPv6 path is easy to miss — but IPv6-only users, and anyone on a network where the fallback is slow, still hit it.
They should. Resolvers on IPv6-only networks need at least one nameserver they can reach over IPv6, and two or more is the usual recommendation for redundancy. Most managed DNS providers already run dual-stack nameservers.
Receiving mail over IPv4 still works almost everywhere, so IPv4-only mail servers are a warning rather than a failure. If your mail servers do publish IPv6 addresses, they must answer SMTP on them, and an IPv6 address that sends mail needs reverse DNS — Gmail rejects IPv6 mail without it.
No. It only makes the same DNS lookups and HTTPS, HTTP and SMTP connections a visitor or mail server would. It never sends mail — the SMTP check reads the greeting and disconnects.