network problems due to missing answers to AAAA requests (dns resolving)

[Frank Meerkötter]

After installing Kubuntu 9.10 RC1 networking became kind of flaky. It somehow worked but everything was slow and unpredictable. It was most visible while browsing the web. Some pages where loading for ages (5+ minutes), some never finishing to load at all while others were just fine after some initial delay. This problem was not only visible in firefox but also in konqueror.

Wireshark showed that my computer was sending DNS queries to my local DSL router (SpeedPort W303V; an ISP provided blackbox). This DSL router also works as a local DNS-cache which it is advertising via DHCP. This explains why the DNS queries are sent to the DSL router. The traffic log showed further that requests for A records (IPv4) were properly answered but requests asking for AAAA records (IPv6) were never blessed with a reply. The missing answer was triggering some retry mechanism which was resending the AAAA record request a few times. Only after this mechanism timed out, the browser was actually starting to load a page.

The DNS cache in my DSL router is apparently not handling requests for IPv6 address records.

I understand that the problem is to some degree caused by my local DSL router not answering AAAA requests but so far (Ubuntu 9.04) it was not a problem. I am wondering what has changed.

PS. i am not sure if this is actually the right package to report the bug against (libc contains the resolver?).

frank@dexter:~$ cat /etc/host.conf
# The "order" line is only used by old versions of the C library.
order hosts,bind
multi on

ProblemType: Bug
Architecture: i386
Date: Mon Oct 26 00:25:21 2009
DistroRelease: Ubuntu 9.10
NonfreeKernelModules: nvidia
Package: libc6 2.10.1-0ubuntu15
ProcEnviron:
 LANGUAGE=
 LANG=C
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-14.48-generic
SourcePackage: eglibc
Uname: Linux 2.6.31-14-generic i686