Re: [dnsext] Lame Server responses

Tony Finch <dot@dotat.at> Tue, 12 October 2010 10:36 UTC

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Date: Tue, 12 Oct 2010 11:30:30 +0100
From: Tony Finch <dot@dotat.at>
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To: Edward Lewis <Ed.Lewis@neustar.biz>
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Subject: Re: [dnsext] Lame Server responses
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On Mon, 11 Oct 2010, Edward Lewis wrote:
> At 18:52 +0100 10/11/10, George Barwood wrote:
>
> > I agree with BIND, it seems to me that REFUSED is closest to then codes
> > defined by the standard.  I expect either SERVERFAIL or REFUSED will
> > work perfectly well.
>
> From reading the spec, neither really applies.  But I think they are the only
> two choices (from the existing pool). I.e., in REFUSED, the "eg" uses the word
> "wishes" which isn't the issue.

You could view it as not wishing to / refusing to return a referral.

> OTOH, SERVFAIL talks about name server error, which also isn't the
> issue.  Our bias was that it was a system error that caused any earnest
> query to go to a lame server, so we adopted SERVFAIL.

BIND's behaviour makes a useful distinction between lame (REFUSED) and
broken (SERVFAIL).

> > Can you think of any other situation that causes REFUSED to be returned (to
> > a normal query)?
>
> AXFR?  Depends on what's normal.  A server that will only answer queries with
> specific TSIG keys?

Or a recursive server that only provides service to specific networks.
Or a master server that does not permit dynamic updates.

Tony.
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