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AAAA record lookup

See the IPv6 addresses a hostname points to, and check that they look right.

A host name works too, like mail.example.com.

More options

Which DNS server to ask. The default is Cloudflare; pick "the domain's own nameserver" to skip every cache and see exactly what the zone publishes.

Set the DNSSEC OK bit: include RRSIG records and report whether the resolver validated the answer (AD flag).

Try:

What an AAAA record is

An AAAA record maps a hostname to an IPv6 address, such as 2001:db8:220:1::10. It is the IPv6 version of the A record. A hostname that works over both protocols has both records, which is called dual stack.

People look up AAAA records for three reasons. They want to confirm that a site they run is ready for IPv6, find out why IPv6 visitors report problems, or see which addresses a service really uses.

How to check IPv6 readiness

  1. Look up the hostnameUse the exact name your visitors type. Check both the bare domain (example.com) and www, because they can differ.
  2. See whether any AAAA record comes backNo AAAA record means the name is IPv4-only. That still works for almost everyone, because IPv6-only networks can reach IPv4 sites through a translation service.
  3. Test that the address answersAn AAAA record does not prove that the server listens on that address. From a machine with IPv6, run curl -6 -I https://example.com and see whether a response comes back.

What the addresses mean

A normal public IPv6 address starts with 2 or 3. If you see anything else, check it against this table:

You seeWhat it isProblem?
2xxx: or 3xxx:Global unicast (a normal public address)Normal
fe80::Link-localOnly works on one local network. Remove it.
fc.. or fd.. (fc00::/7)Unique local (private)Not reachable from outside your network.
2001:db8::Documentation rangeA placeholder that was never replaced.
::1LoopbackPoints to the visitor's own machine.
::ffff:a.b.c.dIPv4-mappedNot meant for DNS.
64:ff9b::NAT64 prefixMade up by DNS64 resolvers. Owners do not normally publish it.

When IPv6 goes wrong

  • The AAAA record exists, but the server does not listen on IPv6. IPv6-capable visitors try that address, wait, then fall back to IPv4. That causes delays, or complete failures with older clients. Fix the server or remove the record.
  • The firewall only covers IPv4. Hosts often have a separate IPv6 firewall. Check that ports 80 and 443 are open there too.
  • Different content over IPv6. The virtual host or certificate setup may exist for IPv4 only, so IPv6 visitors land on a default page.
  • The address changed. Providers can renumber IPv6. Update the AAAA record to match.
  • Visitors on IPv6-only networks. They reach IPv4-only sites through a translation service (NAT64 with DNS64), which makes up 64:ff9b:: addresses for them. You do not need to publish those.

How the lookup works

LookupOwl asks for type AAAA (code 28) from the resolver or authoritative server you pick and shows each address in compressed form with its TTL. Put it next to the A record lookup to see both families side by side. To read or reformat an address, use IPv6 compress and IPv6 expand.

Shell
dig +short AAAA example.com
nslookup -type=AAAA example.com
curl -6 -I https://example.com

Standards: RFC 3596 (the AAAA record), RFC 4291 (IPv6 addressing), RFC 8305 (Happy Eyeballs v2), RFC 6146 and RFC 6147 (NAT64 and DNS64).

Questions people ask

What does AAAA stand for?

AAAA is just the name of the IPv6 address record. An IPv6 address is four times larger than an IPv4 one, so the record got four As instead of one. The DNS type code is 28, and the format is defined in RFC 3596. It is read exactly like an A record, only the address inside it is longer.

Do I need an AAAA record?

No, it is optional. IPv4-only sites stay reachable for nearly everyone. An AAAA record helps visitors on IPv6-only or IPv6-first networks connect directly, and it is increasingly expected. Add one only when your server really answers on IPv6, because a broken record is worse than none.

Why does my site work on IPv4 but not on IPv6?

Usually the web server or firewall is not set up for IPv6, or the AAAA record holds a wrong address. Test with curl -6 -I https://example.com. If that fails, the problem is on the server side. If the address in DNS differs from the one the server has, update the record.

Can I have an AAAA record without an A record?

Yes. The site is then IPv6-only. IPv6 visitors reach it directly, and IPv4-only visitors cannot reach it at all unless a proxy or CDN sits in front. Most sites keep both records so that everyone can get in.

Is an AAAA record the same as a CNAME to an IPv6 name?

No. An AAAA record holds an IPv6 address. A CNAME holds another name, and that name is then looked up for both A and AAAA records. So a CNAME can lead to IPv6 addresses, but it never contains one itself. See the CNAME lookup for how aliases work.

How do I get an IPv6 address for my server?

Ask your hosting or cloud provider. Most assign one automatically, and many show it in the server's network settings. Once you have it, add it as an AAAA record, make sure the server and firewall accept connections on it, and test with curl -6.

Use it from AI, the API or the command line

Every LookupOwl tool is also a free API and an MCP tool, with no key and no account. This one is dns_lookup. Please be kind to the rate limits.

curl
curl "https://lookupowl.com/api/v1/tools/dns-lookup?q=cloudflare.com"
MCP
claude mcp add --transport http lookupowl https://lookupowl.com/mcp

Description for AI agents · OpenAPI · llms.txt