Headless Service (clusterIP: None) cannot resolve because no pods match the Service selector. DNS returns no A records, stateful applications cannot discover members.
A Headless Service (with clusterIP: None) provides direct pod IP discovery via DNS (no load balancing). When the Service selector does not match any pods, DNS queries return no endpoints. This breaks stateful applications (StatefulSets, clusters) that rely on headless services for peer discovery.
First diagnostic step
Second diagnostic step
Third diagnostic step
Fourth diagnostic step
Additional notes and platform-specific considerations.
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Fifth diagnostic step