The true statement is C: the default namespace exists when a new cluster is created. Namespaces are a Kubernetes mechanism for partitioning cluster resources into logical groups. When you set up a cluster, Kubernetes creates some initial namespaces (including default, and commonly kube-system, kube-public, and kube-node-lease). The default namespace is where resources go if you don’t specify a namespace explicitly.
Option A is false because namespaces are not hierarchical; Kubernetes does not support “namespaces inside namespaces.” Option B is false because within a given namespace, resource names must be unique per resource kind. You can’t have two Deployments with the same name in the same namespace. You can have a Deployment named web in one namespace and another Deployment named web in a different namespace—namespaces provide that scope boundary. Option D is false because not all objects are namespaced. Many resources are cluster-scoped (for example, Nodes, PersistentVolumes, ClusterRoles, ClusterRoleBindings, and StorageClasses). Namespaces apply only to namespaced resources.
Operationally, namespaces support multi-tenancy and environment separation (dev/test/prod), RBAC scoping, resource quotas, and policy boundaries. For example, you can grant a team access only to their namespace and enforce quotas that prevent them from consuming excessive CPU/memory. Namespaces also make organization and cleanup easier: deleting a namespace removes most namespaced resources inside it (subject to finalizers).
So, the verified correct statement is C: the default namespace exists upon cluster creation.
=========
