Ubuntu 16.04 LTS – DNS resolution fails after network config changes

📖 ~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

Hostnames fail to resolve, breaking package access, APIs, and service communication.

Environment & Reproduction

Often follows interface changes, resolver edits, or conflicting NetworkManager settings.

Root Cause Analysis

Incorrect nameserver, resolver overwrite, or routing issues prevent DNS queries.

Quick Triage

Test raw connectivity, query DNS servers directly, and inspect resolver state.

Step-by-Step Diagnosis

Trace name lookup path and identify where query responses are lost.

Solution – Primary Fix

Apply stable resolver configuration and restart network components in order.

Solution – Alternative Approaches

Use local caching resolver or static DNS fallback while root cause is remediated.

Verification & Acceptance Criteria

System resolves internal and external names consistently with low query failure rates.

Rollback Plan

Revert resolver and interface files to the previous validated network profile.

Prevention & Hardening

Standardize network templates and monitor resolver drift across fleet nodes.

Related Errors & Cross-Refs

Temporary failure in name resolution and SERVFAIL responses are common indicators.

Related tutorial: View the step-by-step tutorial for Ubuntu 16.04 LTS.

View all Ubuntu 16.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Consult Ubuntu networking and resolver documentation for persistent DNS configuration.