Each poll process sends NTP packets at intervals determined by the poll program. The program is designed to provide a sufficient update rate for thc clock discipline algorithm, while minimizing network overhead.
As an option of the server command, instead of a single packet, the poll program can send a burst of six packets at 2-s intervals. This is designed to reduce the time to synchronize the clock at initial startup (iburst) and/or to reduce the phase noise at the longer poll intervals (burst). The iburst option is effective only when the server is unreachable, while the burst option is effective only when the server is reachable.