ENDS0 for IPv6

EDNS0 (RFC 2671)
Resolvers can tell their buffer size to servers by an OPT record.

Considerations
AAAA/A6 "glue" records of NS records are meaningful only for IPv6 transport-ready resolvers.
IPv6 is a good chance to deploy ENDS0.

Mandate EDNS0 for IPv6 transport
Must use EDNS0 if DNS querys/answers are carried over IPv6.
The requirement will be included in IPv6 host requirements.