NTPD – Where to Look Up NTPD Logs

ntpd logs basic messages to syslog by default, so where those logs go is dependent on your syslog configuration, but /var/log/messages and /var/log/syslog or common places to look.

ntpd can also generate statistics if statsdir is defined in /etc/ntp.conf and you have some filegen definitions. Here is the documentation for statsdir and filegen.

As far as I can tell, ignore means don't open the adress/port, drop means open but ignore any and all traffic (though it might be able to use them still). So yeah, it seems to need the interface bound..

Reference: http://www.eecis.udel.edu/~mills/ntp/html/miscopt.html#interface