RHEL 9 Chrony time drift and NTP sync issues

📖 ~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 time drifts and causes auth, logging, or cluster consistency problems.

Environment & Reproduction

chronyc tracking reports high offset and sources appear unreachable or unsynced.

Root Cause Analysis

Blocked NTP traffic, wrong servers, virtualization clock issues, or service not enabled.

Quick Triage

Run systemctl status chronyd and chronyc sources -v to inspect sync state.

Step-by-Step Diagnosis

Review /etc/chrony.conf for valid upstream servers and preferred source settings.

Solution – Primary Fix

Allow NTP in firewalld where needed and verify outbound UDP 123 reachability.

Solution – Alternative Approaches

Use chronyc makestep carefully on systems with significant initial clock skew.

Verification & Acceptance Criteria

Avoid conflicting hypervisor time sync if chronyd is authoritative in the guest.

Rollback Plan

SELinux usually permits chronyd defaults; custom confinement should be reviewed if modified.

Prevention & Hardening

Use journalctl -u chronyd –since today to inspect peer and sync transitions.

Related Errors & Cross-Refs

Use at least three reliable NTP sources and monitor drift continuously.

Related tutorial: View the step-by-step tutorial for rhel-9.

View all rhel-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Confirm low offset and stable synchronized state across reboot cycles.