📖 ~1 min read
Table of contents
Symptom & Impact
AIX LPAR time drifts >5 minutes from NTP source; xntpd shows ‘no server suitable’.
Environment & Reproduction
xntpd on 7.3 cannot reach upstream NTP servers behind firewall.
Root Cause Analysis
UDP/123 blocked or NTP server pool unresolved on this LPAR.
Quick Triage
Run lssrc -s xntpd and ntpq -p to view peers.
Step-by-Step Diagnosis
Use ntpdate -q to test reachability without changing time.

Solution – Primary Fix
Switch to chrony equivalent (timed) or fix UDP/123 firewall rules.
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Solution – Alternative Approaches
Force one-off sync with ntpdate -u then restart xntpd.
Verification & Acceptance Criteria
ntpq -p shows reach=377 and offset within +/- 50ms.
Rollback Plan
Revert /etc/ntp.conf from backup and restart xntpd.
Prevention & Hardening
Use at least 3 internal NTP peers and monitor offset.
Related Errors & Cross-Refs
Time-sensitive Kerberos failures, log timestamp skew.
Related tutorial: View the step-by-step tutorial for aix-7.1.
View all aix-7.1 tutorials on the Tutorials Hub →
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
AIX xntpd / NTP configuration documentation.
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