What Is NTP?
NTP — the Network Time Protocol — it synchronises device clocks across a network to a common accurate time source, which is essential for logs, certificates and troubleshooting.
How it works
NTP arranges time sources in strata: stratum 0 is the reference clock (GPS/atomic), stratum 1 servers attach to it, stratum 2 sync from stratum 1, and so on. Devices continuously adjust their clocks by querying their configured servers (UDP port 123), achieving millisecond-level accuracy on a LAN.
Why it matters
Wrong clocks break things quietly: log correlation across devices becomes impossible during incident investigations, certificates fail validation, and scheduled jobs misfire. Configuring NTP is basic device hygiene — see it in the syslog + NTP lab.
Frequently asked questions
What does NTP do?
It keeps device clocks synchronised to an accurate reference time, so logs, certificates and time-dependent operations work correctly across the network.
What is an NTP stratum?
The distance from the reference clock: stratum 1 servers connect directly to an atomic/GPS source, stratum 2 sync from stratum 1, and so on — lower is closer to the truth.
Why does time synchronisation matter for security?
Investigating incidents requires correlating logs across many devices — if their clocks disagree, building an accurate timeline becomes impossible.
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