AAAA record (pronounced quad-A) maps a hostname to an IPv6 address. Same role as an A record, different address family. As IPv6 adoption approaches 50% globally, publishing AAAA records is required to be reachable from all networks.
Record Format
example.com. AAAA 2606:4700:20::681a:d1eDual-Stack
Most reachable services publish both A and AAAA:
example.com. A 104.16.132.229
example.com. AAAA 2606:4700:20::681a:d1eResolvers pick IPv6 first when available (Happy Eyeballs, RFC 8305) but fall back to IPv4 within ~250 ms.
Common Miss
Publishing AAAA for a service that isn’t actually listening on IPv6 causes long timeouts for IPv6-native clients. Always verify port reachability from an IPv6 network before publishing the AAAA record.
Related
Check the A record glossary entry, browse every major DNS record type, and read the DNS definition.