IPv6 nameserver deployment

For those that think IPv6 isn't out there.   From the Alexa top 1M list
as of 2016-12-25.

404357 zones have both IPv4 and IPv6 nameservers
548549 zones have IPv4 only nameservers
8 zones have IPv6 only nameservers

the rest NS or address lookups failed for one reason or another.
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE:  +61 2 9871 4742                  INTERNET: marka(_at_)isc(_dot_)org