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AAAA · type 28

Points a name at an IPv6 address.

Last updated 5 Oct 2026 from the IANA RR TYPE registry

Short answer

AAAA (“quad-A”) is the IPv6 counterpart of A: it maps a name to a 128-bit IPv6 address. Dual-stack services publish both, and modern clients prefer IPv6 when it works, falling back quickly to IPv4 (the “Happy Eyeballs” behaviour).

Type
AAAA
Code
28
Defined in
RFC 3596
IANA description
IP6 Address
Field: Address
IPv6 address, usually written compressed, e.g. 2001:db8::10

How it works

Publishing an AAAA record for a server that doesn’t really answer on IPv6 is a common source of “works for some people” problems, because IPv6-capable visitors try that address first.

Example

www.example.com.  3600  IN  AAAA  2001:db8::10

Example uses reserved documentation names and addresses (RFC 2606, RFC 5737, RFC 3849).

Common mistakes

  • Publishing AAAA for a host that has no working IPv6.
  • Mail servers with AAAA but no reverse DNS (PTR) for the IPv6 address: Gmail requires valid forward and reverse DNS for sending IPs.

How to check yours

To check it, look up the name’s AAAA records and then visit the site from a network that has IPv6: if the record exists but the server doesn’t answer on it, those visitors see delays or failures while IPv4-only visitors see nothing wrong. Removing a broken AAAA record is a valid fix until IPv6 actually works on the server.

For email

SPF ip6: mechanisms and the a/mx mechanisms cover IPv6 sending addresses.

Related record types

APoints a name at an IPv4 address.PTRReverse DNS: maps an IP address back to a name.

Sources

Sources

  1. IANA: Resource Record (RR) TYPEs registry · checked 5 Oct 2026
  2. RFC 3596 · checked 5 Oct 2026