AAAA Record Lookup
See the IPv6 addresses a domain resolves to.
An AAAA record is the IPv6 counterpart to an A record: the same question, a 128-bit answer instead of a 32-bit one. The name is a small joke that stuck — an IPv6 address is four times the size of an IPv4 one, so the record type got four As.
When a domain publishes both A and AAAA records it is dual-stack, and a client with working IPv6 will usually try the IPv6 address first. That preference is why a broken AAAA record is more disruptive than a missing one: browsers using Happy Eyeballs will fall back to IPv4 after a delay, so the site still loads but feels sluggish, and the cause is invisible to anyone testing from an IPv4-only network.
Adding an AAAA record is a commitment, not just a configuration. The address has to be served by something that actually answers on IPv6, including your reverse proxy, firewall rules and application listeners. Publishing the record before that path works end to end is the most common way to make a site slower.
What this tool does
Check IPv6 readiness
An AAAA record is the single requirement for a domain to be reachable over IPv6. Its absence is the whole answer.
Verify dual-stack
Run this alongside the A record lookup. Both present means dual-stack, and clients will generally prefer the IPv6 path.
Full address set
Every AAAA answer is listed in its compressed form, so you can compare them against your provider's allocated ranges.
Diagnose partial failures
A site that is slow or broken for some users but fine for others is often an AAAA record pointing somewhere that is not actually serving.
Frequently asked questions
What is an AAAA record?
An AAAA record maps a hostname to an IPv6 address, exactly as an A record does for IPv4. It is written with four As because an IPv6 address is 128 bits — four times the length of the 32-bit IPv4 address an A record holds.
Does my site need an AAAA record?
It is not required, but it is increasingly worth having. Major mobile networks run IPv6-only internally and reach IPv4 sites through translation, which adds latency and a component that can fail. Publishing an AAAA record lets those clients connect directly.
Why is my site slow for some users after adding an AAAA record?
Almost always because the IPv6 address does not fully work. Clients prefer IPv6 when it is advertised, try it first, and only fall back to IPv4 after a timeout — so every affected visitor pays a delay on connection. Verify the IPv6 path end to end, including firewall rules and whether your web server is actually listening on the address.
What does :: mean in an IPv6 address?
It is compression for one run of consecutive zero groups. 2001:4860:4860::8888 expands to 2001:4860:4860:0000:0000:0000:0000:8888. Because it would be ambiguous otherwise, the notation may appear only once in an address.
Can a domain have both A and AAAA records?
Yes, and that is the normal modern configuration — it is what "dual-stack" means. The two record types are independent, so a name can hold several of each, and clients pick an address family based on their own connectivity.
How do I test IPv6 if my network does not support it?
A DNS lookup like this one works regardless, because the query itself travels over whatever your network supports — you are asking for the record, not connecting to it. Actually testing reachability needs an IPv6-capable network or an external checking service.
Monitor it, don't just check it
One-off checks catch what is broken today. CertNotify watches your certificates, domains, DNS and code continuously and tells you before something breaks.