I'm seeing lots of log messages like these:
May 11 06:54:32 jet ntpd: receive: KoD packet from
2001:dce:2:17a::18 has inconsistent xmt/org/rec timestamps. Ignoring.
... on a home server.
A quick web search suggests that KoD packets are a self-defence
mechanism. Am I (accidentally) abusing s[1-3].ntp.net.nz?