Ubuntu 14.04 LTS DNS lookups time out intermittently

📖 ~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 fail to resolve hostnames, causing sporadic API failures and service latency.

Environment & Reproduction

Observed on systems using dynamic DNS from DHCP or unstable upstream resolvers.

Root Cause Analysis

Resolver configuration churn, packet loss, or overloaded DNS infrastructure causes lookup failures.

Quick Triage

Test name resolution against each configured nameserver and check network path consistency.

Step-by-Step Diagnosis

Inspect resolv.conf generation path, verify resolver reachability, and measure query response times.

Solution – Primary Fix

Pin reliable nameservers, stabilize resolvconf integration, and restart affected services.

Solution – Alternative Approaches

Deploy local caching resolver or route DNS traffic through redundant internal forwarders.

Verification & Acceptance Criteria

dig and application checks consistently resolve critical domains without timeout errors.

Rollback Plan

Restore previous resolver policy and DHCP hooks if static configuration degrades connectivity.

Prevention & Hardening

Monitor DNS latency and configure at least two healthy resolvers per environment.

Related Errors & Cross-Refs

Temporary failure in name resolution, SERVFAIL, and connection timed out messages.

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

Ubuntu DNS troubleshooting guides and recursive resolver operations best practices.