Set Date and Time by ARPA Internet RFC 868
Netdate takes a list of names of Internet hosts as arguments, selects
the one that supplies the best time, and sets the system time
The "best" time is chosen by polling the named hosts once each to find
their times and taking their differences from the local host's time.
These differences are used to find the largest group of hosts whose
times agree with each other within a certain limit. The first host in
the largest group is picked as the best host.