[dns-operations] about answer status

[Jim Reid]

On 8 Jun 2015, at 09:12, Kevin C. <kevin at dnsbed.com> wrote:

> Sometime I got "NOERROR" from the answer, but sometime got "NXDOMAIN".
> At what case the nameserver returns "NOERROR" or "NXDOMAIN" for a non-exist record? Thank you.

A NOERROR response means just that: there was no error. A NOERROR response with an empty Answer Section -- usually known as a NOHOST response -- means "the name that was queried for exists, but not as the requested QTYPE". ie foo.bar exists, but not as an A record (say). An NXDOMAIN response means the answering name server believes the name does not exist as any RRtype at all.

So for the examples you gave, defensor.game.yy.com exists but not as an A record -- a NOHOST response -- while defenser.game.yy.com did not exist at all.

FWIW there's an inconsistency between the two authoritative name servers for game.yy.com. dwdns1.nsbeta.info returns NOHOST while dwdns2.nsbeta.info returns NXDOMAIN for lookups of defensor.game.yy.com QTYPEs.

Incidentally, you seem to be using a very old version of BIND (9.6.1-P2). You should upgrade to one of the currently supported releases: 9.9 or 9.10.