RHEL 8 chronyd Time Drift and NTP Sync Failure

📖 ~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 minutes, breaking Kerberos, TLS validation, and distributed job scheduling.

Environment & Reproduction

On RHEL 8 servers, run chronyc tracking and compare against trusted reference clocks.

Root Cause Analysis

NTP source reachability loss, firewall UDP/123 blockage, or misconfigured chrony pool settings.

Quick Triage

Check systemctl status chronyd, chronyc sources -v, and firewall-cmd rules for NTP.

Step-by-Step Diagnosis

Inspect /etc/chrony.conf, test upstream source latency, and review journalctl -u chronyd.

Solution – Primary Fix

Set correct NTP sources, open required firewall path, restart chronyd, and force makestep when needed.

Solution – Alternative Approaches

Use internal stratum servers and fallback pools to reduce dependency on external connectivity.

Verification & Acceptance Criteria

chronyc tracking reports low offset and stratum is stable with no repeated sync loss.

Rollback Plan

Restore prior chrony.conf and restart chronyd if new source set causes wider time instability.

Prevention & Hardening

Monitor offset thresholds and enforce time sync checks in host health policies.

Related Errors & Cross-Refs

Related: Clock skew too great, TLS certificate not yet valid, and Kerberos preauthentication failed.

Related tutorial: View the step-by-step tutorial for rhel-8.

View all rhel-8 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

See RHEL 8 chrony and time synchronization operational guides.