NTP message format

NTP uses two types of messages: clock synchronization and NTP control messages. All NTP messages mentioned in this document refer to NTP clock synchronization messages. NTP control messages are used in environments where network management is needed. Because NTP control messages are not essential for clock synchronization, they are not described in this document.

A clock synchronization message is encapsulated in a UDP message in the format shown in Figure 6.

Figure 6: Clock synchronization message format

The main fields are described as follows: