NTP from scratch

On RHEL 5 the thing to do is this:
awk ‘/^server/ || /^peer/ {print $2}’ /etc/ntp.conf | grep -v ‘127.127.1.0’ > /etc/ntp/step-tickers
chkconfig ntpd on

On RHEL 6:
chkconfig ntpdate on

On RHEL 7:
systemctl enable ntpdate.service