[dns-operations] OT: NXDOMAIN / public resolvers and zen.spamhaus.org

[Stephane Bortzmeyer]

On Sun, Mar 27, 2011 at 03:22:39PM -0500,
 Lyle Giese <lyle at lcrcomputer.net> wrote 
 a message of 45 lines which said:

> I have also seen it mentioned that using these public resolvers are
> not appropriate for use with mail servers as they may give out
> answers for non-existent domains.  They want to push requests for
> non-existent domains to a custom page for their ad or special search
> pages.

This is *not* a property of "public DNS resiolvers" in general. This
is a property of some systems (OpenDNS, for instance) but, others
clearly stated they won't lie:

http://code.google.com/speed/public-dns/faq.html#nxdomains

The mentioned document
<http://www.spamhaus.org/faq/answers.lasso?section=DNSBL%20Usage#261>
(which carries the same claim) is badly wrong.