From kfm-devel  Thu Dec 07 08:45:33 2006
From: Thiago Macieira <thiago () kde ! org>
Date: Thu, 07 Dec 2006 08:45:33 +0000
To: kfm-devel
Subject: Re: Interesting thing with DNS requests
Message-Id: <200612070945.34014.thiago () kde ! org>
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=46redrik Johansson wrote:
>torsdag 07 december 2006 04:26 skrev Pavel Troller:
>> > How is requiring 15x as much data to do the same thing not a bug?
>> > Both apps running in the same environment implies that this has
>> > nothing to with the DNS server performance--the konqueror client
>> > must be issuing far more DNS requests than the Firefox client.

It is not a bug. The slowness you're experiencing is not caused by the=20
extra DNS round-trips.

=46or whatever reason, kio_http isn't keeping those connections alive, so=20
it's connecting way more often. And for each connect, there's DNS lookups=20
(plural). There is a bug in glibc that causes extra, unnecessary lookups,=20
though. Feel free to report it.

>> Hi!
>>   Isn't it because KDE is by default trying IPv6 first when it detects
>> that the machine is IPv6 enabled ? From my experiences, many DNSs
>> still behave incorrectly on IPv6 (like AAAA or similar) queries so the
>> additional traffic may be caused by this. Try to use tcpdump or
>> wireshark to find, what your machine tries to query from the DNS.

It isn't the case here. The symptom of broken IPv6 replies are things not=20
being found or timing out, instead of taking long to render a page.

>Also if that is the case shouldn't it try IPv6 once and if it fails go
> for plain IP for future requests?

It does. DNS works perfectly in that aspect. The nameserver caches the=20
reply, but unfortunately it doesn't cache a no-reply for a field. I don't=20
know if nscd does.

But, for the same reason we look up again, we don't cache anything in the=20
KDE Libraries: we (I) simply don't want to implement DNS rules in KDE.=20
You have daemons that do that way better than we could. So use them.

=2D-=20
=A0 Thiago Macieira =A0- =A0thiago (AT) macieira.info - thiago (AT) kde.org
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