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From: Tony Kimball <alk@pobox.com>
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Date: Mon,  7 Dec 1998 14:00:10 -0600 (CST)
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Reply-To: alk@pobox.com
To: freebsd-net@FreeBSD.ORG
Subject: Re: resolver behaviour
References: <199812071421.JAA08541@whizzo.transsys.com>
	<199812071515.JAA21169@carp.gbr.epa.gov>
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Quoth Mike Jenkins on Mon, 7 December:
: If  I ask ns1.bozo.com does he know mail.bozo.com and he says NO,
: and I ask ns2.bozo.com does he know mail.bozo.com and he says YES,
: then who is right?

It depends on whether ns2 is providing a working mapping.  
>From the point of view of the closed world of DNS there is
no reason to prefer one answer over another.  Applications,
however, operate in the larger world of the network as a whole.
For an application, a name lookup is just a means to an end:
the formation of a connection to mail.bozo.com, in this case.
Accepting the response of ns1 when ns2 has a good mapping
prevents the application from functioning correctly.  The user
thus encounters the bug.  Accepting the response from ns2
when ns2 has a good mapping avoids the bug.  Accepting the
response from ns2 when ns2 has a bad mapping does no damage
to the user, who again encounters the bug.


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