KCNA Kubernetes Fundamentals Practice Test 24 — 15 Questions

Question 1

Which three components are part of the Kubernetes control plane? (Select THREE)

Accepted Answer

etcd. etcd is a consistent and highly-available key-value store used as Kubernetes' backing store for all cluster data. It stores the entire cluster state, including configuration, secrets, and metadata, and is a core component of the control plane because the API server reads from and writes to it to maintain cluster integrity.

Answer

kube-proxy

Answer

kubelet

Question 2

Which control plane component is responsible for persisting the entire cluster state?

Accepted Answer

etcd. etcd is the distributed key-value store that serves as the single source of truth for the entire cluster state, including all objects (Pods, Services, ConfigMaps, etc.) and their desired and current status. The kube-apiserver is the only component that directly communicates with etcd, ensuring that all state changes are persisted durably and consistently. Without etcd, the cluster would have no record of its configuration or running workloads.

Answer

kube-controller-manager

Answer

kube-apiserver

Answer

kube-scheduler

Question 3

What is the smallest deployable unit in Kubernetes?

Accepted Answer

Pod. A Pod is the smallest deployable unit in Kubernetes because it encapsulates one or more containers that share the same network namespace, storage volumes, and lifecycle. While containers are the runtime processes, Kubernetes schedules and manages Pods as atomic units, meaning you cannot deploy a container directly without a Pod wrapper.

Answer

Node

Answer

Container

Answer

Deployment

Question 4

A developer created a Deployment with image 'myapp:v1' and then ran 'kubectl set image deployment/myapp myapp=myapp:v2'. What is the effect of this command?

Accepted Answer

It updates the Deployment's pod template to use the new image, triggering a rolling update.. The `kubectl set image deployment/myapp myapp=myapp:v2` command updates the pod template within the Deployment's specification to use the new image `myapp:v2`. This change triggers a rolling update, where the Deployment controller creates new pods with the updated image and gradually terminates old pods, ensuring zero downtime. The command does not affect Services, create new Deployments, or restart pods immediately without a rolling update strategy.

Answer

It updates the Service selector to point to pods with the new image.

Answer

It creates a new Deployment named 'v2' with the new image.

Answer

It immediately restarts all pods with the new image.

Question 5

An application requires that a set of Pods each be assigned a unique DNS name that can be used for peer-to-peer communication. Which Kubernetes resource should be used?

Accepted Answer

StatefulSet with a Headless Service. A StatefulSet with a Headless Service is correct because StatefulSets assign each Pod a stable, unique network identity (e.g., pod-name-0.service-name.namespace.svc.cluster.local) that persists across rescheduling. A Headless Service (clusterIP: None) disables load balancing and DNS round-robin, allowing direct DNS resolution to individual Pod IPs for peer-to-peer communication. This matches the requirement for unique DNS names for each Pod.

Answer

Job with a Service

Answer

DaemonSet with a Service

Answer

Deployment with a Service

Question 6

Which Kubernetes object provides a stable IP address and DNS name for a set of Pods?

Accepted Answer

Service. A Service provides a stable virtual IP address and a DNS name (e.g., my-svc.namespace.svc.cluster.local) that remains constant even as Pods are created or destroyed. This enables reliable network access to a dynamic set of Pods selected via labels, abstracting away Pod IP volatility.

Answer

Ingress

Answer

ConfigMap

Answer

Deployment

Question 7

You have a Pod that is in 'Pending' state. What is the most likely cause?

Accepted Answer

The node is out of CPU or memory resources.. A Pod in 'Pending' state indicates that the scheduler has not yet assigned it to a node. The most common reason is insufficient resources (CPU or memory) on any available node, causing the scheduler to fail to find a suitable node that meets the Pod's resource requests. This is a core scheduling failure in Kubernetes.

Answer

The application inside the container crashed.

Answer

The container image is missing.

Answer

The Service does not have any endpoints.

Question 8

Which kubectl command is used to create or update resources defined in a YAML file?

Accepted Answer

kubectl apply -f file.yaml. `kubectl apply -f file.yaml` uses a declarative approach to create or update Kubernetes resources. It sends the YAML configuration to the API server, which compares the desired state with the current state and applies the necessary changes, storing the last-applied configuration in an annotation for future updates.

Answer

kubectl update -f file.yaml

Answer

kubectl create -f file.yaml

Answer

kubectl set -f file.yaml

Question 9

A user wants to ensure that a Deployment undergoes a rolling update with zero downtime, and that new Pods are fully ready before old Pods are terminated. Which field in the Deployment spec controls this behavior?

Accepted Answer

spec.strategy.rollingUpdate.maxUnavailable and maxSurge. `spec.strategy.rollingUpdate.maxUnavailable` and `maxSurge` control how many Pods can be unavailable and how many can be created above the desired count during a rolling update. Setting `maxUnavailable=0` ensures no old Pods are terminated until new Pods are fully ready, achieving zero-downtime updates. `maxSurge` allows extra Pods to be created before old ones are removed, enabling a controlled rollout.

Answer

spec.minReadySeconds

Answer

spec.replicas

Answer

spec.template.spec.containers[].resources

Question 10

Which component runs on every node and is responsible for ensuring that containers are running as specified in Pod manifests?

Accepted Answer

kubelet. The kubelet is the primary node agent that runs on every node in a Kubernetes cluster. It is responsible for ensuring that containers described in Pod manifests (typically provided via the API server) are running and healthy. The kubelet does not manage containers directly; instead, it interacts with the container runtime (e.g., containerd, CRI-O) to create, start, and stop containers as specified.

Answer

kube-proxy

Answer

container runtime

Answer

kube-controller-manager

Question 11

You need to store a database password securely and make it available to a Pod as an environment variable. Which Kubernetes resource should you create?

Accepted Answer

Secret. Secrets are designed to store sensitive data, such as passwords, and can be exposed to Pods via environment variables or volumes.

Answer

PersistentVolume

Answer

ConfigMap

Answer

ServiceAccount

Question 12

You have a Pod that is running but not receiving traffic. You suspect the associated Service's selector does not match the Pod labels. Which kubectl command would you use to check the Service's selector?

Accepted Answer

kubectl describe service . `kubectl describe service ` displays the service's selector field under the 'Selector' section, allowing you to directly compare it with the Pod's labels. This is the most straightforward way to verify if the selector matches the Pod labels, which is essential for traffic routing.

Answer

kubectl get endpoints <service-name>

Answer

kubectl get service <service-name> -o yaml

Answer

kubectl logs <pod-name>

Question 13

Which TWO statements correctly describe the purpose of etcd in a Kubernetes cluster?

Accepted Answer

It stores the cluster state, including all Kubernetes objects.. Etcd is the primary data store for all Kubernetes cluster state, including the configuration and status of every Kubernetes object (Pods, Services, Deployments, etc.). It stores this information as key-value pairs, and the Kubernetes API server is the only component that reads from and writes to etcd directly. Without etcd, the cluster would have no persistent record of its desired or current state.

Answer

It manages network rules for Pod-to-Pod communication.

Answer

It schedules Pods onto nodes based on resource availability.

Answer

It exposes the Kubernetes API for external access.

Question 14

Which TWO are valid reasons to use a Namespace in Kubernetes?

Accepted Answer

To enforce network policies that restrict traffic between Pods in different Namespaces.. Kubernetes NetworkPolicies are namespace-scoped resources that can restrict ingress and egress traffic between Pods in different Namespaces. By default, all Pods can communicate across Namespaces, but applying a NetworkPolicy with a podSelector and namespaceSelector allows you to enforce isolation. Option C is correct because Namespaces provide a logical boundary for resource names, preventing naming collisions when multiple teams or projects deploy objects with the same name within the same cluster.

Answer

To reduce the number of API calls to the control plane.

Answer

To improve application performance by reducing latency.

Answer

To store environment variables for containers.

Question 15

Which Kubernetes control plane component acts as the entry point for all administrative tasks and provides the REST API?

Accepted Answer

kube-apiserver. The kube-apiserver is the front-end of the Kubernetes control plane, exposing the Kubernetes REST API. All administrative tasks, such as creating pods, scaling deployments, and querying cluster state, are performed by sending HTTP requests to this component. It validates and processes these requests before storing the resulting state in etcd.

Answer

kube-scheduler

Answer

etcd

Answer

kube-controller-manager