DNS resolution speed

Hi
I'm dealing with the following problem:

My Linux-applications (e.g. Evolution, Mozilla) take a really long time
to resolve an address. When I use the host program, I get the answer in
a couple of miliseconds, but from the application I wait up half a
minute.

The router, a D-Link DI-614+, acts as a nameserver-proxy. When I trick
to overwrite /etc/resolv.conf with an external nameserver, the
resolution goes fine.

It doesn't seem to affect the Windows-pc's in my network, BTW.
So I'm quite puzzled.

Andreas

On 30 Jan 2005 12:55:02 -0800, (E-Mail Removed) <(E-Mail Removed)> wrote:
> Hi
> I'm dealing with the following problem:
>
> My Linux-applications (e.g. Evolution, Mozilla) take a really long time
> to resolve an address. When I use the host program, I get the answer in
> a couple of miliseconds, but from the application I wait up half a
> minute.
>
> The router, a D-Link DI-614+, acts as a nameserver-proxy. When I trick
> to overwrite /etc/resolv.conf with an external nameserver, the
> resolution goes fine.

If you are using dhcp, configure it to NOT change your nameservers and put
your ISP's nameservers in /etc/resolv.conf.

Note that for connections within your LAN, Linux may be attempting to
resolve connecting LAN IPs (which can cause delays). To eliminate that
problem and originally sluggish SBC nameservers, I run my own caching
nameserver (bind9) with added forward/reverse zones for my LAN.

Thanks for you answer. That was what I basically did. I was just
wondering, wether the delay really is caused by the router, since it
doesn't seem to affect Win-PCs.

On Mon, 31 Jan 2005 07:41:54 -0800, Andreas wrote:

> Thanks for you answer. That was what I basically did. I was just
> wondering, wether the delay really is caused by the router, since it
> doesn't seem to affect Win-PCs.

Another possibility is that it is caused by lookups going to IPv6 first,
then falling back to IPv4 after a long delay. This is a known condition
with the default install of Mandrake 10.1 for example - it comes up almost
daily on the Mandrake forum at linuxquestions.org. It may affect other
distros for all I know, but only Mandrake of the ones I've got running.

A symptom is that nslookup from the shell is really quick, but host
resolution from the browser is really slow.

Does disabling IPv6 make a difference?
--
Mark South: World Citizen, Net Denizen

> Does disabling IPv6 make a difference?

Yes, it does!
Thanks, for the hint. I experienced this behaviour both with SuSE and
Ubuntu, and disabling IPv6 really helped.
Andreas

On Mon, 31 Jan 2005 12:28:57 -0800, Andreas wrote:

>> Does disabling IPv6 make a difference?
>
> Yes, it does!

Cool. Nothing works like disabling the latest technology :-)

> Thanks, for the hint. I experienced this behaviour both with SuSE and
> Ubuntu, and disabling IPv6 really helped.

I'm glad it worked for you. It drove me crazy when it happened to me, and
I was delighted when opjose on linuxquestions pointed out the solution.
--
Mark South: World Citizen, Net Denizen