📖 ~1 min read
Table of contents
Symptom & Impact
Containers fail outbound connections due to name resolution errors after daemon or host restart.
Environment & Reproduction
Affects Ubuntu 18.04 docker hosts using inherited resolv.conf and changing host DNS state.
Root Cause Analysis
Container resolver config points to stale or unreachable DNS endpoints after network stack reinitialization.
Quick Triage
Test DNS inside affected container and compare with host resolver behavior and daemon settings.
Step-by-Step Diagnosis
Inspect daemon.json DNS entries, bridge network config, and container resolv.conf generation path.
Solution – Primary Fix
Set explicit daemon DNS servers, restart docker cleanly, and recreate impacted containers.
Still having issues? Our IT Solutions & Services team can diagnose and resolve this for you. Get in touch for a free consultation.
Solution – Alternative Approaches
Use internal DNS service, custom network plugins, or orchestrator-level DNS policy management.
Verification & Acceptance Criteria
Container lookups succeed consistently across daemon and host reboot cycles.
Rollback Plan
Restore previous daemon DNS config if custom resolver path causes service discovery regressions.
Prevention & Hardening
Document container DNS ownership and include restart resilience tests in deployment pipeline.
Related Errors & Cross-Refs
Link host DNS instability and bridge network conflicts with companion Ubuntu container tutorial.
Related tutorial: View the step-by-step tutorial for Ubuntu 18.04 LTS.
View all Ubuntu 18.04 LTS tutorials on the Tutorials Hub →
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
Consult Docker networking docs, system resolver references, and Ubuntu container operation guides.
Need Expert Help?
If you cannot resolve this yourself, our team offers hands-on Server Management, Managed IT Services, and flexible Support Plans. Contact us today — we respond within one business day.
