The authoritative error that has been cached:
nonexistantName(1) indicates an authoritative name error
(RCODE = 3).
noData(2) indicates an authoritative response with no
error (RCODE = 0) and no relevant data.
other(3) indicates some other cached authoritative
error. At present, no such errors are known to exist.
unresolved(4) is used for 'fixed' entries that are currently unresolved.