🟡 Medium   ⏱ 5–30 min  Last verified: 19 May 2026
Affected versions: RHEL 10.0 RHEL 10.1

📖 ~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

Time drift breaks Kerberos, TLS validation, and scheduled workloads.

Environment & Reproduction

Servers behind restricted egress or misconfigured NTP sources.

timedatectl
chronyc tracking

Root Cause Analysis

chronyd cannot reach valid upstream sources or source selection is unstable.

Quick Triage

Check service state and source reachability.

systemctl status chronyd
chronyc sources -v

Step-by-Step Diagnosis

Review chronyd logs and firewall egress for UDP/123.

journalctl -u chronyd -n 200 --no-pager
firewall-cmd --list-all
Illustrative mockup for rhel-10 — chrony_unsynced
Unsynchronized clock status — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Configure reachable servers and restart chronyd.

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cp /etc/chrony.conf /etc/chrony.conf.bak.$(date +%F)
vi /etc/chrony.conf
systemctl restart chronyd
chronyc makestep
Illustrative mockup for rhel-10 — chrony_synced
Chrony synchronized with sources — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Use local enterprise NTP stratum if internet time sources are blocked.

chronyc add server ntp.internal iburst

Verification & Acceptance Criteria

System reports synchronized and offset remains within policy threshold.

timedatectl status
chronyc tracking

Rollback Plan

Restore prior chrony config if new source list introduces instability.

cp /etc/chrony.conf.bak. /etc/chrony.conf
systemctl restart chronyd

Prevention & Hardening

Monitor offset and stratum in centralized observability platform.

chronyc sourcestats -v
systemctl enable --now chronyd

Leap status not synchronized, no selectable sources.

Related tutorial: View the step-by-step tutorial for rhel-10.

View all rhel-10 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

RHEL chrony administration and time sync best practices.

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