[Dnsmasq-discuss] Odd DNS behaviour for www.freesat.co.uk

[Paul Martin]

On Mon, Feb 17, 2020 at 09:05:34PM +0000, Simon Kelley wrote:

> It's pretty difficult to see what dnsmasq can do here, other than give
> up on caching such negative data.

Agreed.

> A reply _from_a_recursive_server_ which includes a CNAME, but no data
> for the target of the CNAME, contains the implication that the target
> doesn't exist.

Agreed.

> Apart from the zone admins, I think the other responsible parties here
> may be the recursive server you are using, (cloudflare at 1.1.1.1) By
> returning the data they are, they cause the problem.
> 
> Testing here, I see different answers to the query www.freesat.co.uk at
> random,
> 
> 1) SERVEFAIL
> 2) The four A records
> 3) A complete CNAME, including the A record for ghs.googlehosted.com.
> 4) Both 2 and 3 combined.
> 
> I've not observed the incomplete CNAME that you saw, so maybe this has
> been fixed by Cloudflare?

I was seeing this problem earlier (and last week) with several
recursive DNS servers, not just Cloudflare, including Google and
several ISP DNS servers.

A few hours later I can't reproduce it!

It looks like something had been broken and may be in the process of
being fixed.

Thanks for looking.

-- 
Paul Martin <pm at nowster.org.uk>