Re: question about caching of lame servers

>>>>> On Thu, 12 Oct 2006 15:46:48 +0200,[color=blue][color=green][color=darkred]
>>>>> Klaus Darilion <klaus.mailinglists@pernau.at> said:[/color][/color][/color]
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> I tried to test the caching of lame servers in bind9 (9.2.4-1sarge1),
> and reviewing the source code, I came to the conclusion that this
> feature is only used as long as there is at least on authoritative name
> server which is not in the lame-cache. As soon as all authoritative name
> servers of a certain domain are in the "lame" state, bind "restarts" the
> lame settings and tries again although all servers are marked as lame.[/color]
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> Is my conclusion correct?[/color]

That's basically correct.
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> If yes, is there an option to change this behavior (if all servers are
> marked as lame bind should not try at all)?[/color]

Not with 9.2.4, but BIND 9.4 caches the lame information per
<qname,class,type> and doesn't try any lame server (whether or not
there is a non-lame server):

1880. [func] The lame cache is now done on a <qname,qclass,qtype>
basis as some servers only appear to be lame for
certain query types. [RT #14916]

I think this implements what you want to see.

(Note: the behavior in 9.2.4 made sense because there are known
(broken) nameservers that behave as being lame only for certain query
types. See Section 2.2 of draft-ietf-dnsop-bad-dns-res-06.txt)
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> Further, I not only want to cache lame name servers, but also name
> servers which are down. Is this possible?[/color]

Not exactly, but the fact that a server is down is cached as
a penalized RTT, which makes that server less preferred in subsequent
server selection.

JINMEI, Tatuya
Communication Platform Lab.
Corporate R&D Center, Toshiba Corp.
[email]jinmei@isl.rdc.toshiba.co.jp[/email]