Look in to what shodan is, its a service dedicated to portscanning the internet. With ipv4 you can easily scan every ip, with ipv6 you need some mechanism to di

Look in to what shodan is, its a service dedicated to portscanning the internet. With ipv4 you can easily scan every ip, with ipv6 you need some mechanism to discover addresses. This very much looks like they joined the ntp pool soley to harvest and portscan addresses.