π ~1 min read
Table of contents
Symptom & Impact
Name resolution intermittently fails, breaking package mirrors and API calls.
Environment & Reproduction
Observed under resolver failover, packet loss, or stale resolv.conf updates.
Root Cause Analysis
Unstable upstream DNS and inconsistent resolver configuration cause query failures.
Quick Triage
Validate reachability to DNS servers and compare lookup behavior across tools.
Step-by-Step Diagnosis
Collect dig/nslookup tests, check resolver config, and inspect network paths.
Solution – Primary Fix
Set reliable resolvers, correct resolver file management, and flush stale cache.
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Solution – Alternative Approaches
Run local caching resolver or direct critical apps to hardened DNS endpoints.
Verification & Acceptance Criteria
Repeated lookups succeed with stable latency and no timeout spikes.
Rollback Plan
Reinstate prior resolver chain if new upstream introduces regressions.
Prevention & Hardening
Use redundant DNS providers and active DNS health monitoring.
Related Errors & Cross-Refs
May appear with apt mirror failures and intermittent TLS handshake errors.
Related tutorial: View the step-by-step tutorial for Ubuntu 14.04 LTS.
View all Ubuntu 14.04 LTS tutorials on the Tutorials Hub β
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
Ubuntu resolver configuration and DNS diagnostics guides.
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