Re: mwscdn.ru issue

Hi Andrey,

On Fri, 2023-12-15 at 18:47 +0300, Andrey Sedletsky via Pdns-users
wrote:
> Good day!
> Andrey Sedletsky, PJSC MGTS (Moscow City Telephone Network)
> One of our clients contacted us with a problem about the inability to
> resolve the resources of their zone through the DNS servers (pdns-
> recursor) of our network (mwscdn.ru ).
> In this case, the problem is of a floating nature.
> If you look at the server cache, you can see negative entries for NS
> servers in their zone when the resource is resolved
> topf66787c7.mwscdn.ru
> (at the same time, the resource itself resolves successfully):

DNSViz [1] reports that the nameservers respond NXDomain for AAAA
queries. When this gets into the cache, the resolver will indeed decide
that the name does not exist.

This is a problem with the auhtoritative servers. They should not send
NXDomain for *types* that don't exist, but a NOERROR with the SOA in
the AUTHORITY section of the response. See RFC 2308 Section 1, on
NODATA [2].

Good luck in solving this issue.

Cheers,

Pieter

1 - https://dnsviz.net/d/ns2.mwscdn.ru/ZX_27w/dnssec/
2 - https://datatracker.ietf.org/doc/html/rfc2308