Comment 1 for bug 995137

Other distros: debian.org is also listed at worldipv6launch.org as going live on IPv6 by June 6.

To be live for IPv6-only sites, you'll also need to have at least one of your DNS servers live on IPv6 and
with an AAAA record for that address. Since the DNS servers for ubuntu.com are ns{123].canonical.com,
and canonical.com is also served by the same three name servers, you'll also have to add a glue record
in .com that gives the AAAA address(es) of your name servers. (Otherwise, IPv6-only clients who look
up ubuntu.com will be unable to look up e.g. ns1.canonical.com since they'd have no accessible path from .com
to ns1.canonical.com.) You add the glue records at your DNS registrar.

It would be particularly useful if the software update mirrors worked from IPv6-only sites, since otherwise,
machines on IPv6-only networks won't get security updates.