KCNA Kubernetes Fundamentals Practice Test 15 — 15 Questions

Question 1

Which command creates a Deployment named 'nginx-deployment' from the image 'nginx:1.25' and exposes it on port 80?

Accepted Answer

kubectl create deployment nginx-deployment --image=nginx:1.25 --port=80. The `kubectl create deployment` command is the standard way to create a Deployment resource in Kubernetes. The `--image=nginx:1.25` flag specifies the container image, and the `--port=80` flag sets the container port in the pod template spec, which allows the Deployment to expose the container on port 80.

Answer

kubectl run nginx-deployment --image=nginx:1.25 --port=80

Answer

kubectl apply -f nginx-deployment.yaml

Answer

kubectl expose deployment nginx-deployment --type=ClusterIP

Question 2

A pod is running a Java application that occasionally leaks memory. After a few hours, 'kubectl describe pod' shows the container exited with OOMKilled. You want to automatically restart the container but ensure the application has enough memory. What should you do?

Accepted Answer

Increase the memory limit in the container's resources.limits and add a liveness probe that triggers on high memory usage. Increasing the memory limit in resources.limits provides the Java application with more memory headroom, reducing the likelihood of OOMKilled terminations. Adding a liveness probe that triggers on high memory usage ensures the pod is restarted proactively if memory consumption approaches the limit, maintaining availability while the underlying memory leak is addressed.

Answer

Set restartPolicy: OnFailure in the pod spec

Answer

Use a DaemonSet instead of a Deployment

Answer

Set terminationGracePeriodSeconds to 0

Question 3

Which component runs on every Kubernetes node and ensures that the containers in a pod are running?

Accepted Answer

kubelet. The kubelet is the primary node agent that runs on every Kubernetes node. It receives PodSpec definitions from the API server and ensures that the containers described in those PodSpecs are running and healthy. It continuously monitors container status and takes corrective actions, such as restarting containers that have failed, making it the correct answer.

Answer

kube-proxy

Answer

kube-scheduler

Answer

container runtime

Question 4

A Kubernetes cluster has multiple worker nodes. You create a Pod without any node selector. The scheduler places the pod on a node, but the pod remains in 'Pending' state. 'kubectl describe pod' shows '0/1 nodes are available: 1 node had taint {node-role.kubernetes.io/master: }, that the pod didn't tolerate'. What does this indicate?

Accepted Answer

The node has a taint that the pod does not tolerate. The error message explicitly states that one node had a taint (`node-role.kubernetes.io/master`) that the pod did not tolerate. Taints and tolerations are a Kubernetes mechanism that allows nodes to repel pods unless the pod has a matching toleration. Since the pod was created without any tolerations, the scheduler could not place it on the tainted node, leaving it in 'Pending' state.

Answer

The pod has a resource request that exceeds the node's capacity

Answer

The node is cordoned and should be uncordoned

Answer

The node is out of disk space

Question 5

Which Kubernetes object can be used to store sensitive data, such as passwords or API keys, and inject them into pods?

Accepted Answer

Secret. A Secret is the dedicated Kubernetes object for storing sensitive data like passwords, API keys, and tokens. Secrets store data as base64-encoded strings and can be injected into pods as environment variables or mounted as volumes, with optional encryption at rest via etcd or KMS.

Answer

PersistentVolume

Answer

ServiceAccount

Answer

ConfigMap

Question 6

You create a Service of type ClusterIP in the 'default' namespace. You try to reach the Service from a pod in the 'production' namespace using the service name. The connection fails. What is the most likely reason?

Accepted Answer

The pod cannot resolve the DNS name because service DNS names are only resolvable within the same namespace. By default, Kubernetes DNS resolves Service names only within the same namespace. A Service named 'my-svc' in the 'default' namespace is resolvable as 'my-svc' only from pods in the 'default' namespace. From a pod in the 'production' namespace, the DNS name must be fully qualified as 'my-svc.default.svc.cluster.local' to be resolved, otherwise the DNS lookup fails, causing the connection to fail.

Answer

Cross-namespace service access is not allowed by default

Answer

The service has no endpoints

Answer

The service port is not correctly configured

Question 7

Which of the following is true about Kubernetes Namespaces?

Accepted Answer

Namespaces are used to logically isolate resources like pods and services. Kubernetes Namespaces provide a mechanism to logically isolate resources such as Pods, Services, and Deployments within a single cluster. They enable multi-tenancy by partitioning cluster resources among multiple users or teams, each operating within their own virtual cluster. This logical isolation does not include network segmentation by default, but it allows for resource quota enforcement and access control via RBAC.

Answer

Namespaces can be nested

Answer

Namespaces are required for all resources

Answer

Namespaces provide network isolation by default

Question 8

Which two statements correctly describe etcd in a Kubernetes cluster?

Accepted Answer

It is a key-value store that holds cluster configuration and state. etcd is a distributed, consistent key-value store used by Kubernetes to persist all cluster data, including configuration, state, and metadata. It is the single source of truth for the cluster, and the API server reads from and writes to it exclusively. Without etcd, the cluster cannot recover or maintain its desired state, making it a critical component.

Answer

It runs on every worker node

Answer

It manages network rules for Services

Answer

It implements the Kubernetes API

Question 9

Which three components are part of the Kubernetes control plane?

Accepted Answer

kube-controller-manager. The Kubernetes control plane is responsible for maintaining the desired state of the cluster. The kube-controller-manager runs controller processes that handle routine tasks such as node management, replication, and endpoint management, making it a core control plane component.

Answer

kube-proxy

Answer

kubelet

Question 10

Which two commands are valid for viewing information about pods in a namespace named 'production'?

Accepted Answer

kubectl get pods -n production. `kubectl get pods -n production` retrieves a list of all pods in the specified namespace, which is a fundamental command for viewing pod information. Option E is correct because `kubectl describe pod <pod-name> -n production` provides detailed information about a specific pod, including events and configuration, within the given namespace.

Answer

kubectl logs pods -n production

Answer

kubectl get all -n production

Answer

kubectl run pod --image=nginx -n production

Question 11

A Deployment is configured with 'replicas: 3'. After a node failure, only 2 pods are running. What component ensures that a new pod is scheduled to restore the desired replica count?

Accepted Answer

kube-controller-manager. The kube-controller-manager runs the ReplicaSet controller, which detects the mismatch and creates a new pod.

Answer

kube-scheduler

Answer

kubelet

Answer

kube-proxy

Question 12

A Service of type ClusterIP is created to expose a set of pods. How does the Service achieve load balancing to the pods?

Accepted Answer

The kube-proxy component on each node sets up network rules to forward traffic to the pods. Kube-proxy on each node implements load balancing for ClusterIP Services by creating iptables or IPVS rules that distribute traffic from the Service's virtual IP to the backend pods. These rules use a random or round-robin selection (depending on the mode) to forward packets to healthy pods, ensuring no single pod is overwhelmed.

Answer

The API server routes traffic directly to the pods

Answer

The kubelet configures the container runtime to route traffic

Answer

Using a cloud load balancer

Question 13

A pod is stuck in 'Pending' state. 'kubectl describe pod' shows '0/4 nodes are available: 4 Insufficient memory'. What is the most likely cause?

Accepted Answer

The pod requires more memory than any node can allocate. The error message '0/4 nodes are available: 4 Insufficient memory' directly indicates that the pod's memory request exceeds the allocatable memory on every node in the cluster. The Kubernetes scheduler evaluates resource requests (spec.containers[].resources.requests.memory) against node capacity, and if no node can satisfy the request, the pod remains in Pending state.

Answer

All nodes have taints that the pod cannot tolerate

Answer

The pod's liveness probe is failing

Answer

The container image is not found

Question 14

Which of the following is a correct apiVersion for a Deployment in a modern Kubernetes cluster (v1.19+)?

Accepted Answer

apiVersion: apps/v1. `apps/v1` is the stable API version for Deployments in Kubernetes v1.19+, replacing the deprecated `extensions/v1beta1` and `apps/v1beta1` versions. The `apps/v1` API group provides the full set of features for Deployments, including rolling updates, rollbacks, and scaling, and is required for production clusters running v1.19 or later.

Answer

apiVersion: extensions/v1beta1

Answer

apiVersion: v1

Answer

apiVersion: apps/v1beta1

Question 15

What is the smallest deployable unit in Kubernetes?

Accepted Answer

Pod. A Pod is the smallest and simplest unit in the Kubernetes object model. It represents a single instance of a running process in the cluster and encapsulates one or more containers with shared storage and network resources. Containers are not directly scheduled onto Nodes; instead, Kubernetes always schedules and manages Pods as the atomic unit of deployment.

Answer

Node

Answer

Deployment

Answer

Container