unicast: - SNTP client 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. broadcast: - SNTP client operates in a point-to-multipoint fashion. The SNTP server 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. multicast: - SNTP client 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. manycast: - SNTP client operates in a multipoint-to-point fashion. manycast(broadcast)- The SNTP client sends a request to a designated IPv4 local broadcast address.One or more manycast servers reply with their individual unicast addresses.After that the communication between client and server is unicast. manycast(multicast)- The SNTP client sends a request to a designated IPv4 or IPv6 multicast group address. One or more manycast servers reply with their individual unicast addresses. After that the communication between client and server is unicast.This mode is currently not supported because the server is not replying in this case.