Ubuntu 22.04 LTS DNS Resolution Fails with systemd-resolved

📖 ~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

Hostnames fail to resolve, breaking package updates, API calls, and outbound service dependencies.

Environment & Reproduction

Seen on Ubuntu 22.04 LTS with systemd-resolved and netplan-managed interfaces.

Root Cause Analysis

Stub resolver, upstream DNS settings, or netplan DNS overrides are misconfigured or unavailable.

Quick Triage

Verify IP connectivity first, then separate DNS issues from route failures.

Step-by-Step Diagnosis

Inspect resolver state, active DNS servers, and /etc/resolv.conf symlink target.

Solution – Primary Fix

Set valid nameservers in netplan, apply changes, and restart systemd-resolved.

Solution – Alternative Approaches

Configure per-link DNS with resolvectl or use NetworkManager profile DNS settings where appropriate.

Verification & Acceptance Criteria

resolvectl query and apt update both succeed with correct DNS response times.

Rollback Plan

Restore previous netplan YAML and reapply if new DNS entries cause outages.

Prevention & Hardening

Use redundant DNS servers and monitor resolver health in systemd journal logs.

Related Errors & Cross-Refs

Related to netplan syntax errors and default route misconfiguration on cloud VMs.

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

See man resolvectl, man systemd-resolved, and Ubuntu Server network docs.