IBM AIX 7.1 – Common Problem 240 – Diagnosis and Fix

📖 ~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

nslookup fails with SERVFAIL and apps cannot resolve hostnames; ssh by name hangs.

Environment & Reproduction

Hit after /etc/resolv.conf change, DNS server outage, or netsvc.conf ordering issue.

Root Cause Analysis

AIX resolver cannot reach configured nameservers or hosts file precedence is wrong.

Quick Triage

Run nslookup host server and host name with cat /etc/resolv.conf and /etc/netsvc.conf.

Step-by-Step Diagnosis

Inspect netstat -an | grep :53 and try dig if available to test recursion.

Solution – Primary Fix

Update /etc/resolv.conf with reachable nameservers and adjust /etc/netsvc.conf order.

Solution – Alternative Approaches

Add critical entries to /etc/hosts as a stop-gap until DNS is restored.

Verification & Acceptance Criteria

nslookup returns answers under 200ms and apps resolve hostnames normally.

Rollback Plan

Restore previous /etc/resolv.conf from backup if new servers misbehave.

Prevention & Hardening

Use redundant nameservers and monitor query latency from each AIX LPAR.

Related Errors & Cross-Refs

Related to LDAP timeouts, NFS server lookups, and Kerberos KDC location.

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

IBM AIX 7.2 resolv.conf and netsvc.conf reference.