resolve fails when no forwarders but roots configured

[Kevin Darcy]

Jeff Stevens wrote:

>I have a customer complaining he cannot resolve MX for domains like:=20
>ceanet.com.au
>
>I tried it using my own DNS with no forwarders but roots configured, and=
 I=20
>get no results for the domain=20
>
What do you mean by "get no results"? A NOERROR response with 0 answers?=20
An NXDOMAIN response? A SERVFAIL response? A timeout?

>unless I request type ANY. =20
>
That doesn't really prove anything. What you showed was just the=20
referral information for ceanet.com.au, which happened to be in your cach=
e.

>Then, I tried=20
>doing the query using ns1.asiaonline.net.au as the server, and I get no =
A=20
>record for ceanet.com.au but I do get a result if I request MX records.
>
Well, that's perfectly normal, in and of itself; the A record of an=20
email domain is not required to resolve, as long as the name owns at=20
least 1 MX record.

However, I think the real DNS-resolution problem here stems from a=20
mismatch between ceanet.com.au's delegation NS records=20
(ns1.asiaonline.net.au and ns2.asiaonline.net.au) and the NS records=20
being published in the zone itself (ns1.nexon.com.au and=20
ns2.nexon.com.au). Mismatched NS records can cause these kinds of=20
resolution problems, and the problem is exacerbated by the low TTLs that=20
are set on the relevant records.

- Kevin