Ubuntu 18.04 time drift or NTP not syncing

📖 ~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, causing TLS, authentication, or scheduling failures.

Environment & Reproduction

timedatectl shows unsynchronized status and significant offset from reference time.

Root Cause Analysis

NTP service disabled, blocked UDP 123, VM host drift, or bad RTC settings are common.

Quick Triage

Check timezone, verify network access to NTP servers, and inspect timedatectl output.

Step-by-Step Diagnosis

Review timedatectl status, systemctl status systemd-timesyncd, and chrony/ntp logs.

Solution – Primary Fix

Enable NTP sync service, set trusted time sources, and force a step correction.

Solution – Alternative Approaches

Use chrony in unstable networks or configure host-guest time integration for VMs.

Verification & Acceptance Criteria

Clock offset remains small and synchronized state persists after reboot.

Rollback Plan

Restore prior time service configuration if new source configuration is unreliable.

Prevention & Hardening

Monitor drift alerts and maintain multiple upstream NTP sources.

Related Errors & Cross-Refs

Impacts certificate validation, Kerberos tickets, and cron timing behavior.

Related tutorial: View the step-by-step tutorial for Ubuntu 18.04 LTS.

View all Ubuntu 18.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Consult timedatectl, systemd-timesyncd, and chrony administration docs.