BIND this easy to DOS? (nobody?)

[Barry Margolin]

In article <dqavbp$2n85$1 at sf1.isc.org>,
 John Little <jlittle_97 at yahoo.com> wrote:

> > > I believe named caches 'lame servers'? Why does it not cache
> > unreachable
> > > servers?
> 
> It does. From DNS and Bind 4th Ed-Since 4.9 all Bind servers implement
> negative caching..if an authoritative name server responds to a query
> that says the domain name or datatype doesn't exist the name server
> temporarily caches that information too.  
> 
> and further on:
> Name servers can't cache data forever so the administrator must decide
> on a TTL for the zone.  A small ttl creates lots of queries but ensures
> consistency while a large ttl reduces queries but may not be as
> consistent.
> 
> All of the above wa paraphrased from the book.

Neither of those paragraphs addresses the problem the OP wrote about.  
He's not getting *any* response from the nameservers, so there's no 
negative response to cache.

I believe he's absolutely correct.  BIND doesn't cache the fact that a 
particular server is non-responsive, so that it shouldn't bother trying 
to query it at all.

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
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