Fri, Oct 24, 2008 at 08:59:20, Mark_Andrews wrote about "Re: glue records in child zone":

> Except it isn't authoritative. It is GLUE.
> When you query for a zone's NS RRset there is no need to
> return any additional records.
> The time when additional records are necessary is when there
> is a referral. At all other time additional records are
> completely optional.

OK, understood. But there is another question for this case. In the
initial example, query of address of ns1.hq.example.org from NS of
example.org gives only referral response to NSes of hq.example.org, in
spite of record for ns1.hq.example.org is present in the example.org
zone itself. Am I correct that presence of NSes of hq.example.org is
enough to treat by modern named that `hs1.hq.example.org A' shall be
ignored during learning of contents of example.org?

If yes, why f.gtld-servers.net knows IP address of c.gtld-servers.net
and authoritatively tells it in response to direct query?

; <<>> DiG 9.4.2 <<>> @f.gtld-servers.net c.gtld-servers.net a
;c.gtld-servers.net. IN A
c.gtld-servers.net. 172800 IN A

According to your description, it should only respond with NSes list
for gtld-servers.net, and corresponding glue records. In my real case,
the similar query meets only referral answer but not the address