Comment 16 for bug 715141

@paelzer: There was a plan to enable IPv6 on all pools last year: https://community.ntppool.org/t/intention-to-enable-ipv6-by-default-in-2017/91 To my knowledge (and based on my brief checks just now) this didn't happen. I suspect the reasons for this are insufficient time to change the pool implementation, and (possibly) fear that the small number of IPv6 servers in the pool would be overwhelmed.

IPv6 on all ntp.ubuntu.com servers is doable, but subject to Canonical IS work priorities. Best to drop us a ticket about this.