Test your connectivity for World IPv6 Day - Explanation?

[Rémi Després]

Le 8 juin 2011 à 17:34, Rémi Després a écrit :
...
> From here, a MAC OS X in a Free.com customer site, I have run a number of times the "ipv6eyechart.ripe.net" test (a great one BTW).
> All sites have been accessible with IPv6 enabled with two exceptions. 
> 
> T-online is
> - unreachable with IPv6 enabled
> - always reachable with IPv6 disabled
> 
> Akamai dual-test 
> - has been for a long time unreachable with IPv6 enabled (but OK now)
> - has always been reachable with IPv6 disabled

Would anyone have an explanation concerning T-online?
FWIW, the problem existed the day before W6D, and persists after it.

Regards,
RD