Ubuntu 22.04 LTS – DNS resolution fails with systemd-resolved – Fix & Prevention

📖 ~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 updates and outbound connectivity.

Environment & Reproduction

Often follows DNS or interface profile changes.

Root Cause Analysis

Invalid upstream DNS settings or resolver instability causes lookup failure.

Quick Triage

Check resolver service and run direct query tests.

Step-by-Step Diagnosis

Trace local stub and upstream nameserver behavior.

Solution – Primary Fix

Set valid DNS in netplan and restart resolver.

Solution – Alternative Approaches

Apply temporary DNS at interface level during incident response.

Verification & Acceptance Criteria

Domain lookups succeed consistently for package mirrors.

Rollback Plan

Restore prior netplan settings if routes or DNS regress.

Prevention & Hardening

Standardize DNS policy and monitor resolver health.

Related Errors & Cross-Refs

Common with VPN split DNS and proxy configuration issues.

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 networking and systemd-resolved documentation.