How to fix Name or service not known: hostname resolution failed in Kubernetes

KubernetesINTERMEDIATEHIGH

DNS resolution fails for hostnames from within pods. CoreDNS pods are not running, DNS queries timeout, or upstream DNS is unreachable.

What this error means

This error occurs when pods cannot resolve hostnames to IP addresses via DNS. Kubernetes uses CoreDNS to provide DNS services. When DNS is unavailable, misconfigured, or upstream resolvers are unreachable, hostname resolution fails and pods cannot communicate with services.

Typical symptoms

nslookup or getent fails with "Name or service not known"
Pods cannot resolve Kubernetes service names
External hostname resolution fails (google.com, etc.)
DNS queries timeout after 5-10 seconds
CoreDNS pods not running or crashing
API server unreachable (cannot resolve "kubernetes" service)
wget/curl fails with "Name or service not known"

Common causes

CoreDNS pods not running or evicted
CoreDNS ConfigMap corrupted or misconfigured
Upstream DNS server unreachable (8.8.8.8 blocked)
Network policy blocking DNS port 53
Node firewall blocking port 53 (UDP/TCP)
Pod /etc/resolv.conf pointing to non-existent nameserver
CoreDNS logs showing plugin errors

How to fix "Name or service not known: hostname resolution failed"

1Step 1

First diagnostic step

2Step 2

Second diagnostic step

3Step 3

Third diagnostic step

4Step 4

Fourth diagnostic step

5Step 5

Advanced notes

Additional notes and platform-specific considerations.

Related errors

Official resources & further reading

📚Kubernetes Official Documentation
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Kubernetes Docs: DNS for Services and Pods(Official Docs)
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Kubernetes Docs: Debugging DNS Resolution(Official Docs)
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Stack Overflow: Kubernetes DNS issues(Stack Overflow)