Help me understand this a bit...

Nicholas Leippe nick at leippe.com
Fri Mar 2 12:16:57 MST 2007


On Friday 02 March 2007 11:49, Corey Edwards wrote:
> On Fri, 2007-03-02 at 11:42 -0700, Nicholas Leippe wrote:
> > On Friday 02 March 2007 11:15, Corey Edwards wrote:
> > > On Fri, 2007-03-02 at 10:59 -0700, Nicholas Leippe wrote:
> > > > Sounds like DNS.
> > >
> > > That could be. 20 seconds for a DNS lookup is ridiculously too long. If
> > > it is a DNS problem, you really should get that sorted out. I recommend
> > > putting a sniffer on your box while you run your network tests. Then
> > > you can see what exactly is going on.
> >
> > It's slow because it's not working--it's timing out.
>
> Yes, and that's improper behavior. It could be the AAAA queries that
> Stuart mentioned. It could be that their DNS server is down. It could be
> doing reverse lookups for an unconfigured 0.168.192.in-addr.arpa. I
> could see any one of those being a problem. My point is that turning off
> DNS resolution by using only IP address only fixes the symptoms and not
> the cause.

Understood.  My other point, however, is that for a production MySQL server, 
it can be advantageous to remove possible points of failure or slowdown--thus 
I turn off name resolution on MySQL and remove the possibility.

> Network problems are often solved by prodigious use of packet sniffers
> and I recommend their use to everyone.

I wholeheartedly agree.

> BTW, did you know that Chuck Norris can sniff packets just by grabbing the
> cat5 with his hand? I'm sure he could fix up that DNS server with a good
> round-house kick.  




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