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Short answer

Namespaces split one cluster into groups of resources. Names must be unique inside a namespace but not across namespaces, and namespaces cannot nest.

Built-in namespaces

• default for objects with no other namespace. [S2]
• kube-system for objects the Kubernetes system creates. [S2]
• kube-public readable by everyone, and kube-node-lease for node heartbeats. [S2]

For production, create your own namespaces instead of using default, and avoid the reserved kube- prefix. [S1]

Claims

• id: C1 claim: Namespaces isolate groups of resources within a single cluster. source: S1 evidence: "namespaces provide a mechanism for isolating groups of resources within a single cluster"
• id: C2 claim: Avoid creating namespaces with the prefix kube-. source: S1 evidence: "Avoid creating namespaces with the prefix kube-"
• id: C3 claim: default is the namespace for objects with no other namespace. source: S2 evidence: "The default namespace for objects with no other namespace"
• id: C4 claim: kube-system holds objects created by the Kubernetes system. source: S2 evidence: "The namespace for objects created by the Kubernetes system"

Sources

• [S1] Namespaces. Kubernetes Authors. https://kubernetes.io/docs/concepts/overview/working-with-objects/namespaces/ . License: CC BY 4.0 (kubernetes/website). Accessed 2026-11-04.
• [S2] Share a Cluster with Namespaces. Kubernetes Authors. https://kubernetes.io/docs/tasks/administer-cluster/namespaces/ . License: CC BY 4.0 (kubernetes/website). Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_9rbj06yb,
  author = {{iinventedlight}},
  title = {{Kubernetes namespaces}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/kubernetes-namespaces/},
  note = {Permanent ID iil:note:9rbj06yb. License: CC-BY-4.0.},
}

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