The command nomodify ntp acl signifies NTP Clients must be denied ntpq(1) and ntpdc(1) queries which attempt to modify the state of the server (i.e., run time reconfiguration).Queries which return information shall be permitted.

The command noquery ntp acl signifies Deny ntpq(1) and ntpdc(1) queries by NTP Clients. But Time service shall not be affected.

The command nopeer ntp acl signifies NTP Clients shall be denied access if unauthenticated packets which would result in mobilizing a new association is sent.

The command notrap ntp acl signifies NTP Clients shall be declined to provide mode 6 control message trap service to matching hosts. The trap service is a sub-system of the ntpq(1) control message protocol which is intended for use by remote event logging programs.

The command KoD ntp acl signifies When an access violation happens by NTP Clients, the server must send the KoD (kiss-o'-death) packets. KoD packets are rate limited to no more than one per second. If another KoD packet occurs within one second after the last one, the packet is dropped.