NHS Network Time Protocol guidance

NTP is a networking protocol for clock synchronisation between computer systems over packet-switched, variable-latency data networks.  Find background information on NTP.

This document provides:

• guidance on why we should use NTP (policy statements)
• a set of requirements and aspects that should be considered when selecting the right NTP services to use
• standards and best practice guides on NTP implementations
• a categorisation of some types of providers that could be used to provide an NTP service

NHS organisations must carry out their own risk assessment to determine clinical and operational requirements for their NTP solution.

NHS Digital provides an NTP service for HSCN consumers who wish to use it.

The HSCN NTP service is provided to all HSCN-connected organisations on only the following 2 IP addresses.

• 155.231.231.3
• 155.231.231.4

Any and all other IP addresses configured for the HSCN NTP service must be removed as those services will be decommissioned in the near future, and without notice.

All organisations connected to HSCN, or who deal with health and social care services within the UK, should ensure they configure a time synchronisation service with 2 sources of stratum three or better (the hierarchical layers of time sources used in the NTP are known as strata). This ensures that consistent time is used across all systems and devices.

NHS Digital's Protective Monitoring Controls. This includes references to the NCSC’s GPG13 and ISO27001/27003 standards.

NCSC Security monitoring Guidance and logging for Security purposes.