📖 ~1 min read
Table of contents
Symptom & Impact
Hostnames fail to resolve intermittently, disrupting package management, APIs, and browser access.
Environment & Reproduction
Direct IP connectivity works while domain queries time out or return inconsistent responses.
Root Cause Analysis
Resolver misconfiguration, unreliable upstream DNS, and network manager overwrite behavior are common triggers.
Quick Triage
Test raw network connectivity, then compare behavior using alternate public and local DNS resolvers.
Step-by-Step Diagnosis
Inspect resolver configuration files and query latency patterns to identify failing DNS path segments.
Solution – Primary Fix
Set stable nameservers, enforce resolver persistence, and restart networking services to apply corrections.
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Solution – Alternative Approaches
Deploy local caching resolver or internal DNS forwarder to improve reliability and response times.
Verification & Acceptance Criteria
Repeated DNS queries succeed with low latency and no recurring resolution failures in logs.
Rollback Plan
Revert resolver file and network manager changes if name resolution for internal domains regresses.
Prevention & Hardening
Use redundant DNS servers and monitor resolution error rates across production endpoints.
Related Errors & Cross-Refs
Often occurs with apt fetch failures, browser timeout errors, and service discovery disruptions.
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
Review Ubuntu resolver documentation and enterprise DNS operational best practices.
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