What is NTP?

NTP stands for Network Time Protocol. It is a protocol with which devices and systems synchronise their clocks with a reliable time source over a network.

NTP is essential for correct log ordering, process control and security in both IT and OT environments.

🎯 Why is NTP important?

• Ensures time consistency in logs and alarms
• Supports security mechanisms such as certificate validation and audit trails
• Synchronisation of data in SCADA, Historian, Batch Control
• Essential for forensic investigation and incident analysis
• Reduces errors in time-sensitive control

⚙️ How does NTP work?

• Devices connect to an NTP server via UDP port 123
• The server sends a timestamp in response
• The client adjusts its system clock
• NTP automatically compensates for network delays
• Internal clocks are gradually adjusted to avoid sudden jumps

🧱 Typical NTP hierarchy

Stratum 0 – GPS, atomic clock or radio time → Stratum 1 – Directly connected NTP server (e.g. on site) → Stratum 2 – Servers on your network (e.g. Domain Controller, firewall) → Clients – PLCs, SCADA, workstations, Historian

🏭 NTP in OT networks

• Historian and Batch Control require accurate timestamps
• Alarm Management depends on the correct sequence of events
• Redundancy and failover only work properly with synchronised time
• In OT environments, an internal NTP server is safer than a public one
• Segmentation requires each zone to have a suitable time source

⏱ NTP and alternatives

✅ Benefits of NTP

• Reliable and reproducible time synchronisation
• Easy to implement and maintain
• Necessary for auditing, security and process logic
• Essential in OT convergence and SIEM integration

📌 In summary

NTP ensures that all your systems are aligned on time — crucial for accurate records, security and reliable production automation.