From owner-freebsd-security  Sat Jan 29 12:23:45 2000
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To: igor@physics.uiuc.edu
Cc: mccord@zytek.com, phk@critter.freebsd.dk, sthaug@nethelp.no,
	fbsd-security@ursine.com, freebsd-security@FreeBSD.ORG
Subject: Re: Continual DNS requests from mysterious IP
From: sthaug@nethelp.no
In-Reply-To: Your message of "Sat, 29 Jan 2000 14:09:45 -0600 (CST)"
References: <200001292009.OAA22881@alecto.physics.uiuc.edu>
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> However, the second method seems to provide more desired (?) result:
> If you try to send an nslookup request about an outside domain
> to the server from an outside host, it will respond as "query refused".
> In the first case (using "allow-recursion"), the server will not
> refuse the query, but rather will respond with the root-servers information.

This is on purpose. The idea of the "allow-recursion" option is to limit
the amount of work that a disallowed client can ask from your server. This
means that it will either return a referral, or an answer from its cache.
But it will *not* perform any new queries on behalf of a disallowed client.

The amount of work to return a "query refused" is about the same as that 
of returning a referral or an answer from the cache.

Steinar Haug, Nethelp consulting, sthaug@nethelp.no


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