BRev AAAA record — name to IPv6 address
An AAAA record is the IPv6 counterpart of an A record. The name comes from size: an IPv6 address is 128 bits, four times the 32 bits of an A record, so the type was named with four As. The value is a single IPv6 address in the usual colon-hex form, with :: compressing the longest run of zero groups.
Publishing both A and AAAA makes a name dual-stack, and modern clients then run Happy Eyeballs (RFC 8305): they try IPv6 and IPv4 nearly in parallel and use whichever connects first. That is excellent for users and treacherous for operators, because a completely broken IPv6 path is invisible to anyone whose client falls back quickly — the site works for you and is slow or unreachable for a subset of visitors whose fallback is slower or absent.
The rule that follows: only publish an AAAA record for an address you have actually tested end to end. A record that points at an address the firewall does not permit, or a load balancer with no IPv6 listener, is worse than having no AAAA record at all — the address without the record is simply not tried.
What a AAAA record looks like
Type 28 · IPv6 address. Zone-file form below — owner name, TTL, then the record and its RDATA.
| Name | TTL | Record | What it means |
|---|---|---|---|
| example.com. | 3600 | AAAA 2606:2800:21f:cb07:6820:80da:af6b:8b2c | A full IPv6 address at the apex. Dual-stack when an A record exists alongside it. |
| www.example.com. | 3600 | AAAA 2001:db8::1 | :: compresses one run of zero groups — 2001:0db8:0000:…:0001. Only one :: per address. |
| ipv6.example.com. | 300 | AAAA 2001:db8:0:1::a | A deliberately IPv6-only name, useful for testing the path without affecting the main site. |
The mistakes that break production
Publishing an AAAA record before the IPv6 path works
The classic dual-stack outage. Clients with IPv6 connectivity try the AAAA first; if the address is unreachable or the firewall drops it, they stall until Happy Eyeballs falls back — and older clients do not fall back at all. Test the address directly (curl -6) before it goes in the zone.
Assuming the site is fine because it works for you
Your client may be IPv4-only, or falling back so fast you never notice. Test explicitly from an IPv6-capable network, or use an IPv6-only test name. A broken AAAA typically surfaces as scattered “the site is slow for me” reports rather than a clear outage.
Query a AAAA record now
The box below is seeded with example.com. Choose AAAA as the type and press Look up — the query goes from your browser straight to Cloudflare or Google over DNS-over-HTTPS, with no server of ours in the path.
DNS is the internet's address book: it turns a name like example.com into the addresses and service endpoints machines actually connect to. Every record has a type (what kind of fact it states) and a TTL (how long resolvers may cache it).
Record types
| Type | What it stores |
|---|---|
| A | IPv4 address |
| AAAA | IPv6 address |
| CNAME | Canonical name (alias) |
| MX | Mail exchanger (priority target) |
| TXT | Text — SPF, verifications, DKIM, arbitrary data |
| NS | Authoritative nameservers |
| SOA | Start of authority (serial, refresh, retry, expire, minimum) |
| SRV | Service locator (priority weight port target) |
| CAA | Which CAs may issue certificates |
| PTR | Reverse DNS (IP → name) |
| DNSKEY | DNSSEC public key |
| DS | Delegation signer (DNSSEC chain of trust) |
| HTTPS | HTTPS service binding (ALPN, ECH, hints) |
| SVCB | General service binding |
| TLSA | DANE — pin certificates in DNS |
| NAPTR | Name authority pointer (SIP/ENUM) |
TTL & “propagation”
DNS changes don't “push” anywhere — resolvers simply keep the old answer until its TTL runs out, then fetch the new one. So a change “propagates” in at most the old record's TTL. Planning a change? Lower the TTL (e.g. to 300s) a day in advance, make the change, then raise it back. The compare card above shows whether major public caches have picked your change up yet.
FAQ
Why is it called AAAA?
Because an IPv6 address is four times the size of an IPv4 address — 128 bits against 32 — so the record type was named with four As. It is usually said as “quad-A”.
Do I need an AAAA record?
Not required, but increasingly worthwhile: mobile networks in particular are heavily IPv6, and IPv6-only clients reach an IPv4 site only through a translation layer. Add one when the path is genuinely tested — never speculatively.
Can a name have both A and AAAA records?
Yes, and that is the normal dual-stack configuration. Clients choose between them with Happy Eyeballs, preferring IPv6 when it connects promptly.