Bug#563552: libc: resolver doesn't fallback to secondary dns-server when first is ipv6 and unreachable

[Aurelien Jarno <aurelien@aurel32.net>]

tag 563552 + unreproducible
tag 563552 + moreinfo

Luca Bruno a écrit :
> Package:  libc6
> Version:  2.10.2-2
> Severity: normal
> Tags:     ipv6
> 
> Standard glibc resolver (ie. gethostbyname()&co., symptomatically
> observed in all programs using it) doesn't use secondary DNS nameserver
> even if correctly set, when the first one is an ipv6 one and is
> temporarily unavailable.
> 
> Let's say /etc/resolv.conf contains just two nameserver lines, like
> this:
> nameserver 2001:1418:10:2::2
> nameserver 8.8.8.8
> 
> If the first one doesn't reply, the second one is never tried. tcpdump
> shows that no connection to that is even attempted.
> The fallback mechanism works, instead, when the primary is ipv4
> (unavailable itself, too).
> 

It is not something I am able to reproduce here, so it may be due to
your configuration setup.

How do you test that? Using "getent ahosts"?
Do you have ipv6 available on the machine?
Have you changed /etc/gai.conf or have other lines in /etc/resolv.conf?

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net