question about caching of lame servers
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
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