AAAA record lookup
Enter a domain to see whether it publishes IPv6 (AAAA) addresses and which ones. The result compares four public resolvers with the domain's own nameserver, so you can see whether IPv6 is set up and up to date.
What an AAAA record is
An AAAA record maps a hostname to an IPv6 address, such as 2001:db8::10. It is the IPv6 counterpart of the A record and is defined in RFC 3596. The name comes from size: an IPv6 address is 128 bits, four times the 32 bits of an IPv4 address. IPv6 addresses are written as eight groups of hex digits. Leading zeros can be dropped, and one run of all-zero groups can be shortened to a double colon.
A and AAAA records are independent, and a name can have either or both. Clients on networks with IPv6 usually try the AAAA address first and fall back to IPv4 when it fails. Browsers use a technique called Happy Eyeballs (RFC 8305) to race the two so that a broken IPv6 path only costs a short delay. Publishing an AAAA record therefore means your server, firewall, and web server configuration all have to answer on that address, not just the DNS entry.
Example AAAA records
example.com. 3600 IN AAAA 2001:db8:85a3::8a2e:370:7334The bare domain has one IPv6 address. The double colon stands for the run of zero groups in the middle.
www.example.com. 300 IN AAAA 2001:db8:1::a www.example.com. 300 IN AAAA 2001:db8:1::bTwo IPv6 addresses for www, so IPv6 visitors are spread across two servers, just as several A records spread IPv4 visitors.
example.com. 3600 IN AAAA ::ffff:192.0.2.10An IPv4-mapped address. It is only an IPv4 address in IPv6 notation and does not give the site real IPv6 reachability.
How to read your result
- No AAAA records found
- If neither the public resolvers nor the source-of-truth row show an AAAA record, the name is IPv4-only. That is not a fault, and many sites are set up this way. Visitors on IPv6-only networks still reach you through their carrier's translation service.
- Compare it with the A result
- Each lookup checks one record type, so run the A lookup too. The IPv4 and IPv6 addresses should belong to the same host or CDN. An AAAA address from a different provider than the A address often means the AAAA record was left behind after a migration.
- The source-of-truth row
- This row shows the AAAA records your DNS provider publishes right now. If public resolvers still show an address you have already deleted, they are serving a cached copy until its TTL runs out. If the source still shows it, the deletion never happened.
- Its own TTL
- AAAA records carry their own TTL, separate from the A record's. When you plan a move, lower both TTLs, or IPv6 visitors may keep reaching the old address long after IPv4 visitors have switched.
Common AAAA record problems
- Stale AAAA after changing hosts
- This is the most common IPv6 problem. You update the A record to the new server but leave the old AAAA record in place, so visitors on IPv6, including many mobile networks, keep reaching the old server. The usual symptom is that the site works on Wi-Fi but shows the old version or an error on a phone. Update or delete the AAAA record at the same time as the A record.
- The server does not listen on IPv6
- The record exists but the web server only binds to IPv4, or the firewall blocks ports 80 and 443 over IPv6. Browsers fall back after a short delay, but command-line tools, monitoring services, and other servers may simply fail. Make the web server listen on the IPv6 address (in nginx, a listen [::]:443 line) and open the firewall for IPv6, or remove the record until IPv6 works.
- Virtual host or certificate bound to IPv4 only
- Some server configurations attach a site or its certificate to a specific IPv4 address. Requests arriving over IPv6 then get a default site or a certificate error. Bind the site to the IPv6 address as well, or to all addresses.
- Malformed or placeholder addresses
- Typing mistakes such as two double colons in one address, IPv4-mapped values like ::ffff:192.0.2.10, or documentation addresses copied from a tutorial produce a record that is useless or rejected. Copy the exact IPv6 address from your host's control panel.
Other record lookups
Frequently asked questions
How do I check if my domain has IPv6?
Run this lookup with AAAA selected. If any resolver and the source-of-truth row show an address, the domain publishes IPv6. To confirm it actually works, the server also has to answer on that address, which DNS alone cannot show.
Is an AAAA record required?
No. A site with only A records works for practically everyone, because IPv6-only networks translate to IPv4 for their users. Adding AAAA lets IPv6 clients connect directly, but only add it once your server is reachable over IPv6.
Do I still need an A record if I have an AAAA record?
Yes. Many networks and devices still use IPv4 only, and without an A record they cannot reach you at all. Keep both records and make sure they point to the same site.
Why is my site slow to start loading on some networks after adding IPv6?
If the AAAA address does not answer, clients on IPv6 networks try it first and wait before falling back to IPv4. The page still loads, but every new connection starts late. Fix IPv6 on the server or remove the AAAA record until it works.
What does AAAA stand for?
It is not an acronym in the usual sense. The A record holds a 32-bit IPv4 address, and an IPv6 address is 128 bits, four times as long, so the record type was named with four A's.