🟠 High   ⏱ 5–30 min  Last verified: 19 May 2026
Affected versions: Oracle Linux 10

📖 ~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

Internal hostnames fail to resolve and dependent services cannot connect.

Environment & Reproduction

Often occurs after resolver configuration drift or DHCP changes.

resolvectl status
getent hosts app.internal
cat /etc/resolv.conf

Root Cause Analysis

Wrong DNS search domains, bad upstream servers, or stale cache entries.

Quick Triage

Check active DNS servers and cache health.

resolvectl dns
resolvectl statistics
journalctl -u systemd-resolved -n 60

Step-by-Step Diagnosis

Trace query path and compare network profile DNS settings.

nmcli connection show | grep -i dns
resolvectl query app.internal
resolvectl flush-caches
Illustrative mockup for oracle-linux-10 — terminal_or_shell
resolver configuration checks — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Set correct DNS servers and search domains then restart resolver.

Still having issues? Our IT Solutions & Services team can diagnose and resolve this for you. Get in touch for a free consultation.

nmcli connection modify eth0 ipv4.dns '10.0.0.53 10.0.0.54'
nmcli connection modify eth0 ipv4.dns-search 'internal.local'
nmcli connection up eth0
systemctl restart systemd-resolved
Illustrative mockup for oracle-linux-10 — logs_or_journal
DNS lookup failure logs — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Use static resolv.conf during transition windows.

chattr -i /etc/resolv.conf || true
echo 'nameserver 10.0.0.53' > /etc/resolv.conf

Verification & Acceptance Criteria

Internal zones resolve reliably from the host.

getent hosts app.internal
resolvectl query db.internal

Rollback Plan

Restore previous connection profile if new DNS values break reachability.

nmcli connection reload
nmcli connection up eth0

Prevention & Hardening

Define DNS standards in network templates and monitor resolution latency.

resolvectl statistics
cat /etc/NetworkManager/system-connections/*.nmconnection | grep dns

Related to proxy bypass misconfiguration and stale nscd caches.

Related tutorial: View the step-by-step tutorial for oracle-linux-10.

View all oracle-linux-10 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Oracle Linux DNS and NetworkManager resolver integration docs.

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.