🟠 High   ⏱ 5–30 min  Last verified: 20 May 2026
Affected versions: CentOS Stream 9

📖 ~1 min read

Table of contents
  1. Symptom & Impact
  2. Environment & Reproduction
  3. Root Cause Analysis
  4. Quick Triage
  5. Step-by-Step Diagnosis
  6. Solution – Primary Fix
  7. Solution – Alternative Approaches
  8. Verification & Acceptance Criteria
  9. Rollback Plan
  10. Prevention & Hardening
  11. Related Errors & Cross-Refs
  12. References & Further Reading

Symptom & Impact

System clock drifts by several seconds and logs show NTP failures.

Environment & Reproduction

Firewalls block NTP, or chronyd lost sources.

Root Cause Analysis

All configured sources unreachable or marked falsetickers.

Quick Triage

Run `chronyc sources -v` and `chronyc tracking`.

Step-by-Step Diagnosis

Check firewalld for outbound UDP/123 and any IPv6 issues.

Illustrative mockup for centos-stream-9 — terminal_or_shell
Chrony time drift diagnostics in terminal — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Update `/etc/chrony.conf` with reachable pools and restart chronyd.

Still having issues? Our IT Solutions & Services team can diagnose and resolve this for you. Get in touch for a free consultation.

Illustrative mockup for centos-stream-9 — logs_or_journal
journal and log evidence for Chrony time drift — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Force step on demand with `chronyc makestep`.

Verification & Acceptance Criteria

`chronyc tracking` shows offset near zero and sources active.

Rollback Plan

Restore prior chrony.conf if pool change is incorrect.

Prevention & Hardening

Pin to internal NTP servers with multiple sources.

Pairs with Kerberos/AD auth failures from clock skew.

Related tutorial: View the step-by-step tutorial for centos-stream-9.

View all centos-stream-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

chronyd(8) and chrony.conf(5) man pages.

Need Expert Help?

If you cannot resolve this yourself, our team offers hands-on Server Management, Managed IT Services, and flexible Support Plans. Contact us today — we respond within one business day.