[hobbit] Which DNS query is causing delays

Ward, Martin Martin.Ward at colt.net
Fri Oct 9 15:25:32 CEST 2009


Thanks Henrik, I am not using the --no-ares option so have put the dnslog entry in as you recommend.

Thanks and I'll let you know how I get on.

|\/|artin

> -----Original Message-----
> From: Henrik "Størner [mailto:henrik at hswn.dk]
> Sent: 09 October 2009 12:26
> To: hobbit at hswn.dk
> Subject: Re: [hobbit] Which DNS query is causing delays
> 
> In <1F7B01020EC4D04DA17703634B9E888E0A01CCD1 at ULPGCTMVMAI003.EU.COLT>
> "Ward, Martin" <Martin.Ward at colt.net> writes:
> 
> >I have noticed recently that my bb-test runs are taking a long time to
> >complete, 6500 seconds instead of the maximum of 600. The info on the
> >bb-test results page shows that the DNS tests are taking most of the
> time,
> >but I have around 200 of these, does anyone have any suggestions on
> how
> >I can find out which DNS tests are causing the delays without having
> to
> >click on every DNS test in all of my Xymon website?
> 
> Are you using a local DNS cache ? I would strongly recommend that you
> do - the resolver library in Xymon is pretty aggressive, and has been
> known to knock out DNS servers if you have many hosts (although 200
> doesn't sound like an awful lot).
> 
> It shouldn't take that long unless you're using the standard resolver
> library (i.e. you are running bbtest-net with the "--no-ares" option),
> in which case Xymon cannot control the timeout for the DNS lookup.
> 
> Try running with the option "--dnslog=FILENAME", this will log those
> DNS requests that fail. It is probably one of those.
> 
> 
> Regards,
> Henrik
> 
> 
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> 



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