Currently i see a big sites reachable by DualStack but there are still some (for me) websites that i thought they should be already support IPv6
download.mozilla.org
for Downloading Firefox is using Amazon infrastructure
Name: bouncer-bouncer-elb.prod.mozaws.net
Address: 52.86.71.202
Aliases: download.mozilla.org
Location Ashburn,Virginia,United States,North America
ISP: Amazon Technologies
To see progress goto https://bugzilla.mozilla.org/show_bug.cgi?id=1244282
Ubuntu
https://launchpad.net Addresses: 91.189.89.222, 91.189.89.225 Canonical Ltd
https://answers.launchpad.net/launchpad Addresses: 91.189.89.224, 91.189.89.225
https://wiki.ubuntu.com/ 91.189.89.153
All Ipv6 only no reachable
IPv6 Support in Microsoft Products and Services
https://technet.microsoft.com/en-us/network/hh994905.aspx
Android
IT pros blast Google over Android’s refusal to play nice with IPv6
DHCPv6 is an outgrowth of the DHCP protocol used in the older IPv4 standard – it’s an acronym for “dynamic host configuration protocol,” and is a key building block of network management. Nevertheless, Google’s wildly popular Android devices – which accounted for 78% of all smartphones shipped worldwide in the first quarter of this year – don’t support DHCPv6 for address assignment.
Why the lack of DHCPv6 support is a problem
Current Status of IPv6 Support for Networking Applications
see http://www a9tc97v.deepspace6.net/docs/ipv6_status_page_apps.html ( LINUX/BSD)
Apple Will Require IPv6 Support For All iOS 9 Apps ( but still pending , my comment?)