Technical explanation
In cluster-scope IPAM, the Cilium Operator allocates a PodCIDR to each node from the configured cluster-wide address pool. It records those allocations in each node’s CiliumNode custom resource, specifically under spec.ipam.podCIDRs . The Cilium agent waits for this allocation during startup and then performs host-local allocation of individual pod addresses from the CIDR assigned to its node.
This division of responsibility explains why C is correct. The agent consumes its assigned range and allocates endpoint addresses locally, but it does not independently choose the cluster-wide per-node PodCIDR. The Operator coordinates those ranges to prevent nodes from receiving overlapping allocations.
Options A and D describe Kubernetes host-scope IPAM rather than Cilium cluster-scope IPAM. In Kubernetes host-scope mode, the Kubernetes controller manager assigns PodCIDRs and exposes them through spec.podCIDR or spec.podCIDRs in the standard Kubernetes Node resource. Cluster-scope mode is specifically useful when Kubernetes is not configured to perform that allocation or when Cilium should control the cluster address pool.
Therefore, the managing component and resource are the Cilium Operator and CiliumNode , respectively.
Official references
Cluster-Pool IPAM ; Cluster Scope IPAM .
Study Guide topic: Installation and Configuration.
