REQUIREMENTS

PRE-INSTALL

POST-INSTALL

To use ntpd to keep your time accurate, the minimum required is to find a
public server and add it to /etc/ntp/ntp.conf: "server <ip-address>"

  Public stratum 1 servers: http://www.eecis.udel.edu/~mills/ntp/clock1a.html
  Public stratum 2 servers: http://www.eecis.udel.edu/~mills/ntp/clock2a.html
  
  or use the DNS round robin servers 'pool.ntp.org'

The daemon produces log output into the file /var/log/ntp.log. So you should
think about adding the line "/usr/sbin/rotatelog ntp.log" to your weekly
system crontab file /etc/cron/weekly/syslog.

If you want to use ntpd to synchronize your lan or similar, or get 
synchronization from other devices like radio, I suggest reading the manual.

PRECAUTION

To keep your time as accurate as possible, you should run ntpd continously, as
it works by adjusting the clock by very small intervals (to not disrupt 
programs depending on time). If your clock is way off, you might want to adjust
it with ntpdate first, as ntpd by default does not update your clock when the 
difference is more than 3600 seconds.

Beware of dhcpcd without the -N flag, because it overwrites your ntp.conf
file. Of course it makes a backup, but it's annoying...