Bug#557003: libc6: DNS queries are extremely slowed by ipv6
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
Reply to: