Coming soon. This course is planned; lessons and labs are not available yet. No release date has been announced.
Use NTP and chrony to interpret clock estimates, source selection and service timelines, then diagnose a changed time path from repeated observations.
Intermediate ยท Time service
Linux service configuration, DNS, basic UDP networking, and the distinction between wall-clock and elapsed time.
Given two private clients, explain their chrony source evidence, repair one source failure, and verify the healthy client and remaining accuracy limits.
A focused NTP course on clock estimates, source selection and incident timelines. Observation exercises use chronyd -x, which does not correct the operating-system clock. Clock adjustment needs an isolated virtual machine. This course does not certify UTC accuracy or teach hardware PTP engineering.
3 planned chapters and 6 lesson outlines.
Explain why configured, reachable, selected and accurate are different claims.
Planned task: Model polling, delay and estimated offset for a private source, then compare the prediction with real chronyc source and tracking output.
Changed case to investigate: A second source is reachable but not selected; explain the evidence before changing any configuration.
Planned task: Compare a monotonic interval with wall-clock timestamps and identify which observation can support a duration claim.
Changed case to investigate: A log timestamp jumps while elapsed service time remains steady; avoid inventing a service stall.
Configure a narrow client path and inspect multiple polls without claiming externally verified time.
Planned task: Configure a private chrony source and client allowlist; inspect source reachability and verify an excluded client cannot use the service.
Changed case to investigate: A client moves to another private subnet; update only the intended access boundary and recheck the exclusion.
Planned task: Inspect a dedicated chronyd -x client's tracking estimate and state explicitly that the operating-system wall clock has not been corrected.
Changed case to investigate: The source appears synchronized through a local reference with no external time; qualify the conclusion instead of calling it accurate UTC.
Diagnose one failed client while preserving an independent healthy client and the limits of the evidence.
Planned task: Predict how a wrong address or blocked UDP path should appear, inspect chronyc and network evidence, and repair the demonstrated fault.
Changed case to investigate: DNS resolves correctly but UDP/123 is filtered; revise the diagnosis rather than repeating the first address fix.
Planned task: Independently compare two client reports after a source change, verify repeated selection evidence, and explain why synchronized wall clocks do not impose total event order.
Changed case to investigate: One client's evidence is stale; delay the timeline conclusion and identify what fresh observation is needed.