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Re: Finding the Bottleneck

I agree.

I always thought that doing a local lookup would be far faster than doing
one on a remote dns cache. We use bind, and set the forwarders to 2 other
DNS servers that are only lightly loaded and on the same network.

Additionally, as far as I can see, most emails get sent to the same
moderately large list of domains (eg. aol), so the local DNS server
would've cache them already anyway.


----- Original Message -----
From: "Russell Coker" <russell@coker.com.au>
To: "Rich Puhek" <rpuhek@etnsystems.com>; "Jason Lim"
Cc: <debian-isp@lists.debian.org>
Sent: Friday, June 08, 2001 6:18 PM
Subject: Re: Finding the Bottleneck

On Friday 08 June 2001 05:47, Rich Puhek wrote:
> In addition to checking the disk usage, memory, and the other
> suggestions that have come up on the list, have you looked at DNS?
> Quite often you'll find that DNS lookups are severely limiting the
> performance of something like a mailing list. Make sure that the mail
> server itself isn't running a DNS server. Make sure you've got one or

Why not?  When DNS speed is important I ALWAYS install a local DNS.
Requests to have to be faster than any other requests...

> two DNS servers in close proximity to the mail server. Make sure that
> the DNS server process isn't swapping on the DNS servers (for the kind

The output of "top" that he recently posted suggests that nothing is

> with 128 MB of RAM as your DNS server. Also, if possible, I like to
> have the DNS server I'm querying kept free from being the authoratative
> server for any domains (not always practical in a real life situation,
> I know).

How does that help?

If DNS caching is the issue then probably the only place to look for a
solution is djb-dnscache.

http://www.coker.com.au/bonnie++/     Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/       Postal SMTP/POP benchmark
http://www.coker.com.au/projects.html Projects I am working on
http://www.coker.com.au/~russell/     My home page

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