Maintained by: NLnet Labs

[Unbound-users] Question about qtype=any

Tony Finch
Mon Jul 18 19:33:06 CEST 2011


Kevin Chadwick <ma1l1ists at yahoo.co.uk> wrote:
>
> Sendmail uses ANY first though and that's on many many servers.

Sendmail has not made ANY queries for many years, though I believe it
did in the very dim and distant past.

However, qmail *does* make ANY queries in order to canonicalize mail
domains in the envelopes of outgoing messages, i.e. to replace domains
that are CNAME owner names with the corresponding CNAME target names.
This behaviour is buggy in several ways. Firstly, the current SMTP
specification does not require domains to be canonicalized. Secondly,
qmail should use an MX query not an ANY query, since it is looking up a
mail domain not performing DNS diagnostics. Thirdly, it uses a 512 byte
buffer which is too small, and it has no provision for dealing with
truncated replies.

Tony.
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