https://ftp.isc.org/isc/bind9/keys/9.11/bind.keys.v9_11
This includes the new KSK2017 key which is planned to replace the KSK2010
in October 11th, 2018. It is important to have software that ships with
both before September 11th 2018. Anything that bootstraps after that could
have trouble switching.
XXX: pullup-8, pullup-7, pullup-6