Ubuntu 14.04 LTS DNS Resolution Intermittently Fails

📖 ~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

Applications randomly fail hostname lookups and user requests time out.

Environment & Reproduction

Common where static DNS settings conflict with DHCP-managed resolver updates.

Root Cause Analysis

Resolver drift and unstable upstream nameservers create intermittent failures.

Quick Triage

Test direct queries against each upstream server and compare responses.

Step-by-Step Diagnosis

Inspect /etc/resolv.conf ownership, network scripts, and resolver behavior over renewals.

Solution – Primary Fix

Set a single DNS source of truth, restart networking, and validate consistent resolution.

Solution – Alternative Approaches

Use a local caching forwarder to isolate upstream volatility.

Verification & Acceptance Criteria

Repeated dig and service calls succeed before and after interface restarts.

Rollback Plan

Restore previous network profile if new resolver order breaks internal domains.

Prevention & Hardening

Manage resolver config through automation and alert on unauthorized changes.

Related Errors & Cross-Refs

Often appears with apt mirror lookup failures and internal API flapping.

Related tutorial: View the step-by-step tutorial for Ubuntu 14.04 LTS.

View all Ubuntu 14.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

See Ubuntu networking and enterprise DNS operations references.