π ~1 min read
Table of contents
Symptom & Impact
Hostname resolution fails intermittently, causing package, API, and service connectivity issues.
Environment & Reproduction
dig and getent hosts return sporadic timeouts while IP-based access continues working.
Root Cause Analysis
Unstable upstream DNS servers, conflicting NetworkManager profiles, or resolver timeout settings.
Quick Triage
Inspect /etc/resolv.conf target, nmcli connection DNS settings, and query latency with dig.
Step-by-Step Diagnosis
Set reliable DNS servers in the active NetworkManager profile and disable unwanted overrides.
Solution – Primary Fix
Restart affected connection and flush caches where applicable, then retest lookups.
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Solution – Alternative Approaches
Allow outbound DNS traffic to approved resolvers and validate zone policies for interface.
Verification & Acceptance Criteria
Resolver utilities generally run unconfined; focus troubleshooting on network path and profile settings.
Rollback Plan
Run repeated dig/getent tests and confirm application dependency checks pass.
Prevention & Hardening
Restore previous DNS profile if new resolvers fail split-horizon or internal zones.
Related Errors & Cross-Refs
Use redundant DNS endpoints and monitor lookup latency/error rate continuously.
Related tutorial: View the step-by-step tutorial for rhel-9.
View all rhel-9 tutorials on the Tutorials Hub β
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
nmcli connection show; dig example.com; journalctl -u NetworkManager -b
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