NetworkManager DNS Not Updating After Interface Change

📖 ~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

Host keeps using old nameserver entries after network updates.

Environment & Reproduction

Check nmcli con show and inspect /etc/resolv.conf target.

Root Cause Analysis

Confirm whether issue affects one interface profile or all profiles.

Quick Triage

DNS values not set in active profile or profile not reloaded.

Step-by-Step Diagnosis

Update DNS using nmcli con mod and ensure ipv4.ignore-auto-dns as needed.

Solution – Primary Fix

Restart connection with nmcli con down/up and verify resolver output.

Solution – Alternative Approaches

systemctl status NetworkManager should be active and stable.

Verification & Acceptance Criteria

Validate UDP/TCP 53 to upstream resolver from this host.

Rollback Plan

SELinux rarely blocks DNS client operations in standard profiles.

Prevention & Hardening

Use journalctl -u NetworkManager for profile activation details.

Related Errors & Cross-Refs

Template nmcli profile settings in baseline host provisioning.

Related tutorial: View the step-by-step tutorial for rhel-9.

View all rhel-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Restore previous profile config and reactivate the old connection.