CSIR-NPL is the National Metrology Institute (NMI) of India by an act of parliament. It holds the responsibility to realize, maintain and disseminate the Indian Standard Time (IST), which is traceable to Coordinated Universal Time (UTC) with an accuracy of a few nanoseconds. Dissemination of IST is done via various methods, including satellite links, network time services, and calibration of clocks and oscillators. CSIR-NPL also offers services for delay calibrations of satellite timing receivers and measuring the frequency stability of oscillators. CSIR-NPL has maintained the stack of Network Time Protocol Servers (NTP servers) to disseminate IST over the network. It uses a hierarchical, semi-layered system of time sources. NTP servers at CSIR-NPL are designated as stratum 1 NTP servers as these servers consider their time reference directly from the authoritative time source, i.e. UTC (NPLI). Time synchronization plays an important role in the cybersecurity of the nation by enabling the analysis and correlation of events from multiple sources and reconstructing the sequence of events. It ensures reliable authentication, enhances network security, coordinates actions across distributed components, supports the monitoring and control of critical infrastructure, facilitates compliance and auditing and ensures the proper sequencing and validation of transactions To augment and strengthen the cybersecurity in the country, the Indian Computer Emergency Response Team (CERT-In) has issued a directive to all service providers, intermediaries, data centres, body corporates and government organizations to synchronize their ICT infrastructure to the NTP servers of National Physical Laboratory (NPL), National Informatics Centre (NIC), or accurate and standard time sources other than NPL and NIC. Hence, the performance of stratum 1 NTP servers with respect to UTC (NPLI) is important to evaluate and report in public domain. In this paper, the performance of commercially available NTP servers at CSIR -NPL which holds the designation of stratum 1 in the network hierarchy is evaluated with respect to UTC (NPLI). The time offset of the stratum 1 NTP server with respect to the UTC (NPLI) in the laboratory is analysed and reported. The study explores the time synchronization behaviour of stratum 1 NTP server, which may be useful for organizations which are taking time synchronization services from stratum 1 NTP servers which are responsible for nation-wide time synchronization.