KCNA Kubernetes Fundamentals Practice Question
Which TWO of the following are functions of the kube-controller-manager?
⚠ Common exam trap
CNCF often tests the distinction between the kube-controller-manager and the kube-scheduler, so the trap here is that candidates mistakenly think pod-to-node assignment is a controller function, when it is exclusively handled by the scheduler.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Managing replication and ensuring the desired number of pods are running
Option A is correct because the kube-controller-manager runs the ReplicationController/ReplicaSet controller, which continuously reconciles the actual number of running pods with the desired replica count specified in the resource. Option D is correct because the kube-controller-manager includes the node controller, which monitors node health via heartbeats/leases and responds to node failures by marking nodes NotReady and evicting or rescheduling their pods. Option B is incorrect because cluster state is persisted in etcd, not by the kube-controller-manager. Option C is incorrect because the Kubernetes API is exposed by the kube-apiserver. Option E is incorrect because pod-to-node assignment (scheduling) is performed by the kube-scheduler.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Managing replication and ensuring the desired number of pods are running
Why this is correct
The kube-controller-manager runs the ReplicationController and ReplicaSet controllers, which continuously reconcile observed pod counts against the declared replica count, creating or deleting pods to close any gap. This satisfies the stem's requirement for managing replication and maintaining the desired number of running pods.
- ✗
Storing cluster state
Why it's wrong here
Cluster state is persisted in etcd, the distributed key-value store; the kube-controller-manager runs control loops that reconcile desired state, never storing it. It is tempting because the controller-manager reads and writes objects through the API server, so its constant interaction with state can be mistaken for ownership of the storage layer.
- ✗
Exposing the Kubernetes API
Why it's wrong here
The Kubernetes API is exposed by kube-apiserver, which serves REST requests and validates objects; the kube-controller-manager only watches and reconciles resources via that API. It is tempting because controller-manager activity is visible through API objects, so its reliance on the API server can be confused with providing the API itself.
- ✓
Monitoring node health and responding to node failures
Why this is correct
The node controller inside the kube-controller-manager continuously watches node heartbeats; when a node stops reporting, it marks the node NotReady and triggers eviction of its pods, satisfying the stem's requirement for node health monitoring and failure response.
- ✗
Assigning pods to nodes
Why it's wrong here
Assigning pods to nodes is the responsibility of the kube-scheduler, which uses resource requests and constraints to select a node for each unscheduled pod. The kube-controller-manager runs controller loops (e.g., ReplicaSet, Node Lifecycle) but does not perform node assignment. This option is tempting because the controller-manager oversees node health and can evict pods from unhealthy nodes, but it never decides which node a new pod lands on.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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