It declared udp/53 only. The daemon listens on tcp/53 as well, and a resolver is
asked over tcp whenever an answer will not fit in a datagram — so on every
converged machine that port is closed while the service reports itself healthy
and the manifest reads as though the resolver were fully declared.
The same fault as issue 136 in miniature: the declaration covers part of what the
service does, and the gap is silent because nothing compares the two.