Options for timeout in Bind/DNS

[TPZ]

Dnia 1-07-2009 o godz. 19:02 Kevin Darcy napisał(a):
> TPZ wrote:
> > Are there any options for Bind to configure timeout for DNS requests?
> >
> >
> >   
> Short answer: not as far as I know.
> 
> Hopefully you understand that it's the DNS clients, and not BIND itself,
> that implement the main timeout/retry strategy for a DNS query
> transaction. Send a request, if it times out, try another resolver in
> the resolver list, or retry the request. The main determinant of whether
> a request succeeds or fails, therefore, in the face of slow or
> unavailable upstream nameservers, is the client resolver's
> configuration, not BIND's. The applications which call the resolver
> routines on those clients, may also have their own timeout values, which
> can sometimes be significantly shorter than what is set in the client
> resolver. Therefore they will timeout the lookup request before the
> client resolver would have abandoned it.
> 
> BIND itself will time out and fail over quickly -- on the order of
> milliseconds -- between the nameservers it talks to. It will also keep
> track, in its cache, of what nameservers are responding slowly, or which
> are giving invalid answers, and de-prioritize or avoid nameservers in
> those respective categories. So, in practical terms, it is "self-tuning"
> over time, and in a way that is far more sophisticated than setting a
> single "timeout" value could ever hope to accomplish.
> 
> - Kevin
> 
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Thank you for explain.
I experienced some problems with i.e. SSH, because there is an option 
set by default #UseDNS yes. And when DNS is not available (ie via 
/etc/resolv.conf) it is about 30 seconds timeout. Even if you connect 
like this "ssh user at 192.168.100.12" (without DNS domain name) 
application trying contact DNS.
Are you agree with me?