question about caching of lame servers

Barry Margolin barmar at alum.mit.edu
Wed Oct 18 03:57:57 UTC 2006


In article <eh44qj$1bi1$1 at sf1.isc.org>,
 Kevin Darcy <kcd at daimlerchrysler.com> wrote:

> Klaus Darilion wrote:
> > That gives faster timeouts - but I want to get rid of timeouts 
> > completely - of course the first lookup will time out, but the name 
> > servers should be marked as down for some time and sequential lookups 
> > should be avoided.
> >   
> I think you're setting yourself for a very fragile and fickle lookup 
> subsystem, since we're talking primarily about an unreliable protocol 
> (UDP) being used over long-distance networks with varying latencies. 
> Packet delays and drops are commonplace.

But BIND already retries the original queries.  If all the queries to 
all the nameservers for a domain fail, it's unlikely to be due to 
transient problems like this.

And the cached down state would presumably have a reasonable timeout 
(which could be configured in named.conf, of course), so the failure 
shouldn't produce serious problems.

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***



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