KCNA Kubernetes Architecture & Components 2 — Questions and Answers
Question 1: Which component is responsible for watching for newly created Pods with no assigned node and selecting a node for them to run on?
- kube-controller-manager
- kube-scheduler (Correct answer)
- kubelet
- kube-apiserver
Correct answer: kube-scheduler
The kube-scheduler watches for newly created Pods and selects the best node for them based on resource requirements and constraints.
Question 2: What is the primary function of etcd in a Kubernetes cluster?
- Running containerized workloads
- Serving as a consistent and highly-available key-value store for all cluster data (Correct answer)
- Routing network traffic between pods
- Managing container images
Correct answer: Serving as a consistent and highly-available key-value store for all cluster data
etcd is a distributed key-value store that serves as Kubernetes' backing store for all cluster state and configuration data.
Question 3: Which Kubernetes component runs on every node and ensures containers are running in a Pod?
- kube-proxy
- kube-scheduler
- kubelet (Correct answer)
- kube-controller-manager
Correct answer: kubelet
The kubelet is a node agent that runs on every node and ensures the containers described in PodSpecs are running and healthy.
Question 4: What does the Node Controller in kube-controller-manager do when a node becomes unreachable?
- Immediately deletes all Pods on the node
- Marks the node as NotReady and eventually evicts Pods after a timeout (Correct answer)
- Reschedules Pods to other nodes instantly
- Shuts down the cluster
Correct answer: Marks the node as NotReady and eventually evicts Pods after a timeout
The Node Controller marks unreachable nodes as NotReady and, after a configurable eviction timeout (default 5 minutes), evicts Pods from those nodes.
Question 5: Which communication pattern does the kubelet use to report node and pod status?
- kubelet pushes status to etcd directly
- kubelet pulls instructions from etcd and updates nodes
- kubelet reports to the kube-apiserver via HTTPS (Correct answer)
- kubelet receives commands only from kube-scheduler
Correct answer: kubelet reports to the kube-apiserver via HTTPS
The kubelet communicates with the kube-apiserver over HTTPS, both to receive Pod specs and to report status updates.
Question 6: In a highly available Kubernetes control plane, how is leader election typically handled for kube-controller-manager?
- All instances run actively and merge their changes
- One instance is elected leader via a lease object; others remain on standby (Correct answer)
- etcd automatically designates one instance as primary
- The kube-scheduler picks the leader
Correct answer: One instance is elected leader via a lease object; others remain on standby
kube-controller-manager uses leader election with Kubernetes Lease objects so only one instance is active at a time while others remain on standby.
Question 7: What is the role of the cloud-controller-manager in Kubernetes?
- Manages container runtimes on cloud nodes
- Integrates cloud-provider-specific control logic separate from the core Kubernetes binary (Correct answer)
- Handles DNS resolution for cloud services
- Manages TLS certificates for the cluster
Correct answer: Integrates cloud-provider-specific control logic separate from the core Kubernetes binary
The cloud-controller-manager embeds cloud-specific control loops (node, route, service) to allow cloud providers to release features independently of the Kubernetes core.
KCNA Kubernetes Architecture & Components 2
Which component is responsible for watching for newly created Pods with no assigned node and selecting a node for them to run on?