[dns-operations] dnsop-any-notimp violates the DNS standards

bert hubert bert.hubert at netherlabs.nl
Mon Mar 9 15:18:12 UTC 2015

On Mon, Mar 09, 2015 at 11:08:03AM -0000, D. J. Bernstein wrote:
> My "qmail" software is very widely deployed (on roughly 1 million SMTP
> server IP addresses) and, by default, relies upon ANY queries in a way
> that is guaranteed to work by the mandatory DNS standards.

Hi Dan,

The way I read RFC 1034 4.3.2, this is not true. In step 4 we match whatever
we find in the cache, put it in the packet, and move on to step 6.

This means the algorithm might terminate returning only an A record or only
an AAAA record.  Or a TXT record for that matter.

This reading of 4.3.2 makes 'ANY' queries to resolvers fragile. It might not
return what you need.

Do you think I read 4.3.2 wrong? Or is there another RFC that updates the


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