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List:       namedroppers
Subject:    Re: the KEY debate
From:       Rob Austein <sra+namedroppers () hactrn ! net>
Date:       2002-08-07 22:48:15
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At Wed, 07 Aug 2002 16:31:31 -0500, Eric A. Hall wrote:
> 
> And to answer your next question, sendmail and qmail both use qtype=all
> out of the box.

This was a bad idea in 1985, and has not improved with age.  It can
return the wrong answer under certain conditions, and the defence
against that failure mode involves at least as many queries as one
would have made if one just queried first for the MX then falling back
to querying for the A.

This is not hypothetical.  We tracked a series of whacky mail failures
at MIT-LCS in the early 1990s to another implementation of this same
bad idea (in a then-current version of MMDF).  We replaced the QTYPE=*
query with the obvious MX and A queries and the problems went away.

MMAILR never did this.  Postfix doesn't do this.  It's a misfeature.
Plow it under and sow its burial site with salt.  Don't defend it.

We now return you to your regularly scheduled interminable debate
about the true purpose of DNS.

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