AAAA record
Name to IPv6 address. Four As. Still forgotten in allow-lists that only list v4.
AAAA maps a name to a 128-bit IPv6 address. Dual-stack hosts ask for A and AAAA. If you only firewalled the v4 path, v6 is still open.
A name can have A, AAAA, or both. Many clients prefer v6 when it exists. An AAAA you did not mean to publish is a quiet exposure, not trivia.
See also: A record, CNAME, TTL.
Fact source: IETF RFC 3596, AAAA.