John Maguire 32a7c04498 Return NODATA instead of NXDOMAIN for missing record types (#1668) ...

The DNS responder was setting RCODE=NXDOMAIN (Name Error) any time the
answer section was empty, including for names that exist in the
lighthouse but lack a record of the requested type (e.g. an AAAA query
for a v4-only host). Per RFC 2308 §2.1, NXDOMAIN means "the domain
referred to by the QNAME does not exist", and per RFC 2308 §2.2 a name
that exists with no record of the requested type must be answered with
RCODE=NOERROR and an empty answer section (NODATA).

The practical fallout: busybox ping in Alpine issues AAAA first, treats
NXDOMAIN as a hard failure, and never falls through to A. Returning
NODATA lets the resolver continue to the A query as it should.

Track whether any queried A/AAAA name is known in either map and only
set RcodeNameError when no queried name exists at all.

2026-04-21 16:32:48 -04:00

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