Bug#268631: force preference of IPv4 over IPv6
On Sun, Apr 26, 2009 at 07:40:49PM +0100, Barak A. Pearlmutter wrote:
> > ... Google is fully IPv6-enabled
>
> Sort of. I've used http://ipv6.google.com/. But Google has IPv6
> disabled at the DNS level for www.google.com, albeit perhaps only for
> some requests. Watch:
WRONG:
$ host -t aaaa www.google.com
www.google.com is an alias for www.l.google.com.
www.l.google.com has IPv6 address 2001:4860:a004::68
They may do that based on geodns, but at least it is done for some
subnet including mine.
> $ curl --ipv4 --silent --show-error http://www.google.com | wc -c
> 218
> $ curl --ipv6 --silent --show-error http://www.google.com | wc -c
> curl: (6) Couldn't resolve host 'www.google.com'
>
> Why? Because enabling it would break or degrade performance on many
> IPv6-enabled clients, which would blithely prefer IPv6 and get
> sporadic service. If the clients defaulted to preferring IPv4, then
> this wouldn't be a problem, and Google could put IPv6 addresses into
> all DNS records, without risk. That's what I'd like to see happen.
> It won't until clients default to "prefer IPv4."
Your arguments do not work. Google *is* using IPv6, they consider IPv6
ready for the public.
> So Google is your IPv6 poster child? Watch!
>
> $ ping -c2 www.google.com
> PING www.l.google.com (216.239.59.104) 56(84) bytes of data.
> 64 bytes from gv-in-f104.google.com (216.239.59.104): icmp_seq=1 ttl=237 time=2.57 ms
> 64 bytes from gv-in-f104.google.com (216.239.59.104): icmp_seq=2 ttl=237 time=2.25 ms
>
> $ ping6 -c2 ipv6.google.com
> PING ipv6.google.com(fx-in-x68.google.com) 56 data bytes
>
> --- ipv6.google.com ping statistics ---
> 2 packets transmitted, 0 received, 100% packet loss, time 999ms
>
> $ timeout 60 telnet ipv6.google.com http
> Trying 2001:4860:a003::68...
> Timeout: aborting command ``telnet'' with signal 9
> Killed
>
$ ping -c2 www.google.com
PING www.l.google.com (209.85.227.104) 56(84) bytes of data.
64 bytes from wy-in-f104.google.com (209.85.227.104): icmp_seq=1 ttl=246
time=10.3 ms
64 bytes from wy-in-f104.google.com (209.85.227.104): icmp_seq=2 ttl=246
time=10.3 ms
--- www.l.google.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1003ms
rtt min/avg/max/mdev = 10.352/10.375/10.399/0.104 ms
$ ping6 -c2 www.google.com
PING www.google.com(fx-in-x68.google.com) 56 data bytes
64 bytes from fx-in-x68.google.com: icmp_seq=1 ttl=59 time=12.3 ms
64 bytes from fx-in-x68.google.com: icmp_seq=2 ttl=59 time=12.0 ms
--- ipv6.google.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1005ms
rtt min/avg/max/mdev = 12.067/12.191/12.316/0.166 ms
Looks like your should change your IPv6 provider.
--
Aurelien Jarno GPG: 1024D/F1BCDB73
aurelien@aurel32.net http://www.aurel32.net
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