📖 ~1 min read
Table of contents
Symptom & Impact
System clock drifts significantly, causing authentication failures, job scheduling issues, and log inconsistencies.
Environment & Reproduction
On RHEL 8, run chronyc tracking and chronyc sources to observe unsynchronized status.
Root Cause Analysis
NTP server reachability, incorrect chrony.conf entries, or blocked UDP 123 traffic prevent sync.
Quick Triage
Check systemctl status chronyd, timedatectl, and firewalld rules for NTP service availability.
Step-by-Step Diagnosis
Validate source addresses, DNS resolution, and packet flow while reviewing chronyd logs in journalctl.
Solution – Primary Fix
Update chrony.conf with valid sources, restart chronyd, allow ntp service in firewalld, then verify offsets.
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Solution – Alternative Approaches
Use internal NTP mirrors, fallback pools, or hardware clock sync for isolated environments.
Verification & Acceptance Criteria
chronyc tracking reports synchronized state and offset remains within acceptable operational threshold.
Rollback Plan
Revert chrony.conf to prior known-good version and restore previous firewall state if required.
Prevention & Hardening
Monitor NTP reachability, enforce approved time sources, and alert on offset drift over baseline.
Related Errors & Cross-Refs
Related to TLS certificate validation failures and Kerberos errors caused by clock skew.
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
Use Red Hat chrony documentation and chronyc command references for RHEL 8 time management.
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