🟠 High   ⏱ 5–30 min  Last verified: 30 May 2026
Affected versions: Windows Server 2022

📖 ~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

Pods cannot resolve service names and rollout pipelines fail health checks.

Environment & Reproduction

CoreDNS forwards to upstream resolvers that are blocked or unreachable from cluster network.

kubectl logs -n kube-system deploy/coredns

Root Cause Analysis

DNS forwarding path times out due firewall blocks, route gaps, or bad upstream entries.

Quick Triage

Validate DNS from node and pod network contexts.

Resolve-DnsName kubernetes.default.svc.cluster.local
Test-NetConnection dns01 -Port 53

Step-by-Step Diagnosis

Inspect CoreDNS ConfigMap and service endpoints.

kubectl -n kube-system get configmap coredns -o yaml

Solution — Primary Fix

Set reachable upstream resolvers and allow DNS traffic through policy layers.

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kubectl -n kube-system edit configmap coredns
# update forward . 10.10.10.10 10.10.10.11

Solution — Alternative Approaches

Deploy node-local DNS cache to reduce upstream dependency impact.

kubectl apply -f nodelocaldns.yaml

Verification & Acceptance Criteria

Service and external DNS lookups succeed from test pods.

kubectl run dns-test --image=busybox --restart=Never -- nslookup kubernetes.default

Rollback Plan

Restore previous CoreDNS ConfigMap revision if query failures increase.

kubectl rollout undo deployment/coredns -n kube-system

Prevention & Hardening

Monitor DNS latency and error rates with SLO alerts.

kubectl top pods -n kube-system

Related: kube-proxy endpoint sync delay and CNI packet drops.

Related tutorial: View the step-by-step tutorial for Windows Server 2022.

View all Windows Server 2022 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Kubernetes CoreDNS troubleshooting and Windows node networking docs.

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