The resolver lists in FailedTypes each record type whose query to a
nameserver got no usable reply (none after two tries, an error reply, a
referral, or a truncated reply whose TCP retry failed), and logs it with
the reason unless shutdown cut it short. A nameserver that answered no
type has failed, as before.
The watcher saves such a type in failedTypes, keeping the previous
check's records, leaves it out of the comparison with other nameservers
on that check, and compares the kept records with the next answer. With
nothing to keep, it is also in unknownTypes and not compared until it
answers. Change messages leave out what was not compared. A nameserver
whose A, AAAA or CNAME query failed is no answer when following a CNAME
or resolving addresses.
Model: opus-5-5
The port check removed the saved port state of every address no
configured name resolves to. A name whose nameservers all timed out
or failed is saved with no records, so its addresses looked gone and
lost their port state; when the nameservers answered again it was
recorded afresh, and a port that opened or closed meanwhile was not
notified.
An entry is now kept when one of the names saved on it is configured
and none of its nameservers answered on its last check, and such a
name stays on the entry when the port is checked again for another
name. A name whose nameservers answer with no addresses still loses
it, and so does a name no longer configured.
Model: opus-5-5
LookupAllRecords now returns each nameserver's response, so the
watcher saves its status: ok when it answered, NXDOMAIN and no records
included, and error with the reason when it timed out, answered
SERVFAIL or REFUSED, or could not be reached. A nameserver that starts
failing sends NS Failure and one that answers again sends NS Recovery.
A failing nameserver is left out of the record change and
inconsistency comparisons. The resolver used to report REFUSED and
network errors as an answer with no records; they are now errors. A
lookup cut short by its context now returns an error instead of a
failure of the nameserver it was querying.
Model: opus-5-5