SntpClientOperModes
A SNTP client may operate in one of several modes. ------------------------------------------------------- -- Any or all of these modes MAY be supported on a -- device. ------------------------------------------------------- disabled - SNTP is not operational. No SNTP requests are sent from the device nor are any received SNTP messages processed. unicast - SNTP operates in a point-to-point fashion. A unicast client sends a request to a designated server at its unicast address and expects a reply from which it can determine the time and, optionally, the round-trip delay and local clock offset relative to the server. multicast - SNTP operates in point-to-multipoint fashion. The SNTP server uses a multicast group address to send unsolicited SNTP messages to clients. The client listens on this address and sends no requests for updates. broadcast - This operates in the same manner as multicast mode but uses an IP local broadcast address instead of a multicast address. The broadcast address is scoped to a single subnet, while a multicast address has Internet wide scope. anycast - SNTP operates in a multipoint-to-point fashion. The SNTP client sends a request to a designated IPv4 or IPv6 local broadcast address or multicast group address. One or more anycast servers reply with their individual unicast addresses. The client binds to the first one received, then continues operation in unicast mode.