🟡 Medium   ⏱ 5–30 min  Last verified: 18 May 2026
Affected versions: Windows Server 2016

📖 ~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

Containers can reach IP addresses but fail hostname resolution, breaking service discovery.

Environment & Reproduction

Appears on NAT networks after DNS server changes or HNS policy drift.

docker run --rm mcr.microsoft.com/powershell:lts-nanoserver-1809 nslookup bing.com

Root Cause Analysis

Container endpoint DNS settings are stale or point to unreachable resolvers.

Quick Triage

Inspect container resolv.conf equivalent and host DNS reachability.

Get-DnsClientServerAddress
Test-NetConnection  -Port 53

Step-by-Step Diagnosis

Review HNS network JSON and DNS policy fields for the NAT network.

Get-ContainerNetwork | ConvertTo-Json -Depth 5
Get-WinEvent -LogName Microsoft-Windows-DNS-Client/Operational -MaxEvents 200
Illustrative mockup for windows-server-2016 — terminal_or_powershell
Container DNS and resolver diagnostics — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Recreate NAT network with explicit DNS server settings.

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docker network rm nat
docker network create -d nat --subnet 172.26.0.0/16 --gateway 172.26.0.1 nat
Illustrative mockup for windows-server-2016 — event_or_log_viewer
DNS resolution recovery verification — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Use transparent networking for workloads requiring direct enterprise DNS behavior.

Verification & Acceptance Criteria

Hostname lookups succeed from test containers and application dependencies resolve.

Rollback Plan

Restore prior network definition and host DNS policy if namespace collisions occur.

Prevention & Hardening

Version-control container network definitions and validate DNS after every host change.

Related to NRPT policy entries, DNS suffix mismatch, and outbound firewall DNS blocks.

Related tutorial: View the step-by-step tutorial for Windows Server 2016.

View all Windows Server 2016 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Microsoft Learn: Windows container DNS behavior and NAT networking operations.

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