timeouts when using secondary dns

[Ton Voon]

Hi!

Just to let you know that I've made a change to CVS today, reported  
by Pawel Malachowski, where it looked like the plugins were making  
too many calls to resolver/DNS when the plugins were compiled with  
IPv6 options enabled.

This should reduce the occasions of timeouts. However, I do like the  
idea of making the Nagios server a caching name server too...

Ton

On 9 Nov 2006, at 22:25, Steve Shipway wrote:

> We dealt with this by installing a local caching-only nameserver on  
> the Nagios host itself.  This also took a lot of the load off of  
> the main nameservers.   So, resolv.conf was set to use 127.0.0.1 by  
> default and have our normal name servers as secondaries.  A nice  
> sideeffect was that it vastly sped up the name resolution.
>
> Steve
>
> --
> Steve Shipway
> ITSS, University of Auckland
> (09) 3737 599 x 86487
> s.shipway at auckland.ac.nz
>
>
>
>
> From: nagios-users-bounces at lists.sourceforge.net [mailto:nagios- 
> users-bounces at lists.sourceforge.net] On Behalf Of stucky
> Sent: Friday, 10 November 2006 6:57 a.m.
> To: Az
> Cc: nagios
> Subject: Re: [Nagios-users] timeouts when using secondary dns
>
> Yey !! That totally did it. Thx AZ I hadn't even considered messing  
> with the resolver cuz I was sure it was a nagios issue so I had to  
> fix nagios.
> If that wasn't a text book example of how well mailinglists can  
> work then I don't know what is...
>
> thx
>
> On 11/7/06, Az <az at whoever.org> wrote:
> stucky wrote:
> > I use the check_by_ssh plugin for most of my stuff and I noticed  
> that
> > if the primary nameserver is unavailable nagios starts freaking out.
> > All of a sudden all plugins time out. I tested it using the 'host'
> > command and it only takes about 1 second longer to lookup hosts  
> using
> > the secondary nameserver.
> > The default timeout for check_by_ssh is 10 seconds. I cranked it  
> up to
> > 30 and still I get timeouts. I'm not sure I understand that one.
> > Has anyone else seen this.
> We had a similar issue in that our primary DNS was doing strange  
> things,
> and it quite often took 5 or even 10 seconds to perform a DNS lookup.
> What we were seeing was 70% of service checks (and subsequently host
> checks) failing by timing out. The key was the multiple of 5 seconds.
> The resolver timeout on, say, RHEL3 is based on RES_TIMEOUT in
> resolv.h... which was 5 seconds.
>
> We added the following to our resolv.conf , and found the problems  
> went away:
>
>     options timeout:2 rotate
>
> This sets the timeout for waiting for a reply to 2 seconds, and tells
> the resolve to rotate through your 'nameserver' entries rather than
> always hitting #1, then #2, etc.
>
> Cheers.
>
>
>
>
>
>
>
> -- 
> stucky
>
>
> This message has been scanned for viruses by MailController.
>
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http://www.altinity.com
T: +44 (0)870 787 9243
F: +44 (0)845 280 1725
Skype: tonvoon


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Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
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