[hobbit] Which DNS query is causing delays

Milan Kocian milon at wq.cz
Fri Oct 9 16:10:45 CEST 2009


On Fri, Oct 09, 2009 at 11:26:23AM +0000, Henrik Størner wrote:
> 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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> 
> 

Hello,

when we are talking about, I have one question in this area (DNS).
I don't understand why http tests resolve hostnames when you explicitly
define ip address in test. Is this intention to make dns test together ?
(I have small patch to disable it :-).

Thank for answer,

Regards,

-- 
Milan Kocian



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