📖 ~1 min read
Table of contents
Symptom & Impact
Package updates fail because hostnames cannot be resolved through DNS.
Environment & Reproduction
Frequently observed after netplan or DNS resolver changes.
Root Cause Analysis
systemd-resolved is misconfigured, unreachable, or using invalid nameservers.
Quick Triage
Verify resolver service, nameservers, and outbound network path.
Step-by-Step Diagnosis
Test DNS resolution and verify connectivity to Ubuntu mirrors.
Solution – Primary Fix
Set valid DNS servers in netplan and apply network configuration.
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Solution – Alternative Approaches
Use temporary resolvectl DNS settings for immediate package recovery.
Verification & Acceptance Criteria
DNS lookups and apt metadata refresh both complete successfully.
Rollback Plan
Revert netplan YAML from backup and reapply previous network profile.
Prevention & Hardening
Validate netplan changes with generate before applying in production.
Related Errors & Cross-Refs
Related to Could not resolve host and temporary name resolution failure.
Related tutorial: View the step-by-step tutorial for Ubuntu 22.04 LTS.
View all Ubuntu 22.04 LTS tutorials on the Tutorials Hub →
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
Ubuntu 22.04 netplan and systemd-resolved documentation.
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