Bug#557003: libc6: DNS queries are extremely slowed by ipv6
Pedro Ribeiro a écrit :
> On Thu, Nov 19, 2009 at 12:03 AM, Aurelien Jarno <aurelien@aurel32.net> wrote:
>> On Wed, Nov 18, 2009 at 09:40:03PM +0000, Pedro Ribeiro wrote:
>>> Package: libc6
>>> Version: 2.10.1-7
>>> Severity: important
>>>
>>> When using Firefox, Google Chrome, Opera, Synaptic and other applications which use DNS, I always have to wait a long time (2 to 10 seconds) for a host to resolve (i.e. messages like "Resolving host", "Looking up http://whatever";, etc).
>>>
>>> I always thought that this was a problem of my internet connection.
>>> I could never track the origin of it until finally like 2 hours ago I stumbled across this:
>>> https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/417757
>>>
>>> To test if I had this problem, I opened up Firefox and got to about:config, entered ipv6 and set "network.dns.disableIPv6" to false. Immediately, every DNS query was extremely fast and browsing was up to par to my high speed internet connection.
>>> To do a definite test, I added "ipv6_disable=1" to my kernel command line and after that all the applications above were having much faster DNS queries.
>>>
>>> This is a rather serious bug that I have been experiencing ever since upgrading to testing (right after lenny's release), and always blamed on my ISP/wireless connection/configuration/etc, while finding it strange that every Mac or Windows PC near me using the same connection appeared to be much faster on DNS queries.
>>>
>>> I guess there must be much more users affected by this and like me, they have no clue why.
>>>
>>> It may be caused by a recent version of libc6, because the bug above is marked as "karmic regression" (the latest ubuntu is the karmic one, 9.10) and a friend of mine who is using lenny doesn't appear to have the same problem.
>>>
>>> Pardon me if this as already been reported, I searched around but could not find a Debian version of this bug.
>>>
>> Does adding "options single-request" to /etc/resolv.conf fixes your
>> problems?
>>
>> If so, it is due to a broken DNS server on your ISP side, and a bug
>> in Firefox and other application which explicitely ask to resolve
>> IPv6 adresses by not passing AI_ADDRCONFIG to getaddrinfo().
>>
>> --
>> Aurelien Jarno GPG: 1024D/F1BCDB73
>> aurelien@aurel32.net http://www.aurel32.net
>>
>
> Hi,
>
> you are right! It does solve my problem. But the strange thing is that
> I moved to another country in the last 2 months, but I've had this
> problem in my previous country also. So I guess its an application and
> not a DNS problem?
Are you using the same modem/router and using it as a DNS server?
> What do you think I should do, file a bug with all the respective
> applications, or just wait for the Ubuntu bug to go upstream / sort
> itself out?
There is no real plan to fix it. Maybe implement one more workaround if
we found how broken is your DNS server.
--
Aurelien Jarno GPG: 1024D/F1BCDB73
aurelien@aurel32.net http://www.aurel32.net
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