Troubleshooting erratic network performance

cameron lord trieocorp-PkbjNfxxIARBDgjK7y7TUQ at public.gmane.org
Sat Jun 6 13:59:35 UTC 2009


corrupt arp tables?

bad physical hardware?
 
> Date: Fri, 5 Jun 2009 21:01:43 -0400
> From: jsellens-Iv5KO+h6AVB+Y12zHexnB0EOCMrvLtNR at public.gmane.org
> To: tlug-lxSQFCZeNF4 at public.gmane.org
> Subject: Re: [TLUG]: Troubleshooting erratic network performance
> 
> Oh oh - someone broke rule number one on you: no changes Friday
> afternoon.
> 
> Could there be a DNS resolution problem? Could apache be trying
> to do a reverse lookup on the IP address connecting and be timing
> out? Do the apache access logs show IP addresses or hostnames?
> Can each DNS server in /etc/resolv.conf be reached and succeed
> in doing a forward and reverse lookup? e.g.
> dig @1.2.3.4 asbestos.ss.org
> dig @1.2.3.4 1.5.108.206.in-addr.arpa. ptr
> 
> Does the web page connect to a backend server e.g. mysql?
> I had a slow page problem just the other week, because the
> mysql server couldn't do reverse lookups on the IP of the
> web server, which could be resolved either by fixing DNS
> or adding an appropriate local entry to /etc/hosts.
> 
> You could watch DNS traffic and expect to see answers and
> quick replies with tcpdump, if you know what interface to
> watch.
> 
> Any idea what changed?
> 
> Hope that helps!
> 
> John
> --
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