So if you would like to have a Mac acting as a ntp server, the steps are pretty straightforward. This works on all recent client and server versions of OS X.

1) Unload the ntp plist (most definitely needed on the server OS):
launchctl unload /System/Library/LaunchDaemons/org.ntp.ntpd.plist

2) Modify the ntp-restrict.conf
The following lines in the file:
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery
Should become:
restrict default kod nomodify notrap nopeer
restrict -6 default kod nomodify notrap nopeer

Basically the ‘noquery’ needs to be removed.

3) Load the ntp plist.
launchctl load /System/Library/LaunchDaemons/org.ntp.ntpd.plist

That’s it! Piece of raw brownie (better than cake, trust me).
Then modify whatever box that needs an ntp server to point to you freshly modified Mac.