Assessment of an NTP service calibration over a Local Area Network

Nowadays, timekeeping is an essential component in modern computing. The Network Time Protocol (NTP) is a distributed service based on a hierarchical network protocol used to synchronize computer clocks over a network in an easy and scalable manner. Currently, this protocol is the main mechanism used on the internet to provide a common notion of time to all computers. The Real Instituto y Observatorio de la Armada (ROA) realizes Spanish legal time and disseminates it via the internet from two publicly accessible NTP time servers. In this study, it is assessed the implementation and characterization of two NTP time servers over a Local Area Network in client-to-server and server-to-server modes from the side of NTP protocol and all its functionalities. These measurements aim to analyze the client-to-server mode operation, forcing the polling interval at different values, and to verify the consistency of the results by employing the ppstest tool to compare one pulse-per-second from the UTC (ROA) with the client time offset. This comparison corroborates the proper operation of the NTP time server configured as stratum 1 and referred directly to UTC (ROA), and shows how a real deployment can be professionally deployed with the aim of distributing time over a public service using NTP.