Troubleshooting erratic network performance

[Jamon Camisso]

John Sellens wrote:
> 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

dns looks good though I initially thought it might be that since it 
wasn't just apache slowing down.

> 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.

Different sites using different databases (mysql, postgresql). All are slow.

> You could watch DNS traffic and expect to see answers and
> quick replies with tcpdump, if you know what interface to
> watch.

Still poring through the dumps, not sure what I'm looking for, but 
nothing sticks out either.

> Any idea what changed?

Pretty much nothing server side. Just a tarball and extraction of a php 
webapp. Thanks for the ideas though, still stumped.

Jamon
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