KCNA Practice Test 21 — 15 Questions

Question 1

Which of the following is a benefit of using an orchestrator like Kubernetes?

Accepted Answer

Automatic scaling based on CPU utilization. Kubernetes, as a container orchestrator, provides built-in Horizontal Pod Autoscaling (HPA) that automatically adjusts the number of pod replicas based on observed CPU utilization (or custom metrics). This is a core benefit because it allows applications to handle varying load without manual intervention, improving resource efficiency and availability.

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Direct access to the host kernel for performance tuning

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Guaranteed zero downtime for all updates

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Manual scaling based on traffic spikes

Question 2

What is Helm's role in Kubernetes?

Accepted Answer

A package manager for Kubernetes applications. Helm is a package manager that simplifies deploying and managing Kubernetes applications using charts.

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A CI/CD server

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A security scanner for container images

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A monitoring and logging tool

Question 3

Which API version is correct for a Deployment in modern Kubernetes (v1.29+)?

Accepted Answer

apiVersion: apps/v1. In modern Kubernetes (v1.29+), the `apps/v1` API version is the stable and recommended version for the Deployment resource. The `apps/v1` API has been the default since Kubernetes 1.9, and all older beta versions (e.g., `apps/v1beta2`, `extensions/v1beta1`) have been removed as of Kubernetes 1.16. Using `apps/v1` ensures compatibility with current cluster features and avoids deprecation warnings.

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apiVersion: extensions/v1beta1

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apiVersion: v1

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apiVersion: apps/v1beta2

Question 4

A pod has a liveness probe that returns failure. What action will Kubernetes take?

Accepted Answer

The container will be restarted. When a liveness probe fails, Kubernetes interprets this as the container being in a deadlock or unresponsive state from which it cannot recover without a restart. The kubelet on the node where the pod is running directly restarts the container according to the pod's restart policy (defaulting to Always). This is a container-level action, not a pod-level action, so the pod itself remains on the same node.

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The service endpoint will be removed

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The pod will be deleted

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The pod will be rescheduled to another node

Question 5

Which service mesh component is typically deployed as a sidecar proxy alongside application containers?

Accepted Answer

Envoy proxy. Envoy proxy is the most common sidecar proxy in service meshes like Istio and Linkerd. Istiod is the control plane component, Kiali is a visualization tool, and Prometheus is a monitoring system.

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Kiali

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Istiod

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Prometheus

Question 6

Which TWO of the following are true about Kubernetes Pods?

Accepted Answer

A pod is the smallest deployable unit in Kubernetes. A Pod is the smallest and most fundamental deployable unit in Kubernetes. It represents a single instance of a running process in the cluster and encapsulates one or more containers with shared storage and network resources. You cannot deploy a container directly; you must always wrap it in a Pod.

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Containers in a pod always have isolated filesystems

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Pods are designed to be long-lived and never terminated

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Each container in a pod gets its own IP address

Question 7

You need to run a batch job that processes a queue of 1000 items. The job should run to completion and then terminate. Which Kubernetes resource is BEST suited for this workload?

Accepted Answer

Job. A Kubernetes Job is designed for batch processing tasks that run to completion and then terminate. It creates one or more Pods and ensures that a specified number of them successfully terminate. For a queue of 1000 items, a Job can be configured with a parallelism value and a completions count to process all items and then exit, making it the ideal resource for this workload.

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DaemonSet

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Deployment

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StatefulSet

Question 8

What is the purpose of a liveness probe in a Kubernetes pod?

Accepted Answer

To check if the application is still running; if not, restart the container. A liveness probe in Kubernetes is used to determine if a container is still running and healthy. If the probe fails, the kubelet kills the container and restarts it based on the pod's restart policy. This ensures that applications that have entered a deadlock or hung state are automatically recovered without manual intervention.

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To check if the pod is scheduled on a node

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To check if the container has started successfully

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To check if the application is ready to serve traffic

Question 9

Which TWO statements accurately describe the concept of immutable infrastructure in the context of container orchestration? (Select two.)

Accepted Answer

Container images are versioned and promoted through environments without modification. Immutable infrastructure treats container images as immutable artifacts that are versioned and promoted through environments (e.g., dev, staging, prod) without modification. This ensures consistency and reproducibility, as the same image is deployed across all stages without patching or altering it in place.

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Configuration changes can be applied via SSH into the container

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Containers are updated in place by executing commands inside running containers

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Stateful applications require mutable infrastructure

Question 10

A Deployment manages ReplicaSets and supports rolling updates. You want to change the container image of a Deployment without downtime. What is the recommended approach?

Accepted Answer

Edit the Deployment's pod template spec to use the new image; the Deployment will automatically perform a rolling update. Editing the Deployment's pod template spec triggers an automatic rolling update, which is the recommended approach for zero-downtime updates. The Deployment controller creates a new ReplicaSet with the updated image and gradually scales it up while scaling down the old ReplicaSet, ensuring that a minimum number of pods remain available throughout the process.

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Use kubectl expose to update the image on the service

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Delete the existing Deployment and create a new one with the updated image

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Manually delete all pods one by one; they will be recreated with the new image by the ReplicaSet

Question 11

What is the purpose of a Namespace in Kubernetes?

Accepted Answer

To logically isolate resources like pods and services. Namespaces in Kubernetes provide a mechanism for logically isolating resources such as Pods, Services, and Deployments within a cluster. They enable multiple virtual clusters to coexist on the same physical cluster, allowing for resource scoping, access control, and organization by team or environment (e.g., dev, staging, prod). This isolation is fundamental to multi-tenancy and resource management in Kubernetes.

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To assign IP addresses to services

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To limit the number of pods that can be created

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To provide DNS names for pods

Question 12

What is the primary purpose of a Kubernetes Service object?

Accepted Answer

To provide a stable IP address and DNS name for a set of Pods. The primary purpose of a Kubernetes Service object is to provide a stable network endpoint (a fixed IP address and DNS name) that abstracts and load-balances traffic across a dynamic set of Pods. Pods are ephemeral and can be rescheduled with new IP addresses, so the Service ensures clients can reliably reach the application without needing to track individual Pod IPs.

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To store configuration data that can be consumed by Pods

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To manage rolling updates and rollbacks for Pods

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To persist data beyond the lifecycle of a Pod

Question 13

You have a Deployment named 'web-app' with 3 replicas. You need to scale it to 5 replicas. Which kubectl command should you use?

Accepted Answer

kubectl scale deployment web-app --replicas=5. The `kubectl scale` command is the correct way to adjust the replica count of an existing Deployment. It directly modifies the `spec.replicas` field in the Deployment's desired state, instructing the ReplicaSet controller to create or delete Pods to match the new count. Option B uses the correct syntax `kubectl scale deployment web-app --replicas=5` to achieve this.

Answer

kubectl create deployment web-app --replicas=5

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kubectl edit deployment web-app --replicas=5

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kubectl describe deployment web-app

Question 14

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.

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

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The node is cordoned and should be uncordoned

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The node is out of disk space

Question 15

Which TWO statements about containers are true compared to virtual machines? (Select TWO.)

Accepted Answer

Containers are more lightweight and start faster than VMs. Containers share the host OS kernel and run as isolated processes, requiring no hypervisor or full OS boot. This makes them lightweight (megabytes vs gigabytes) and allows them to start in milliseconds, whereas VMs must boot a full guest OS, which takes seconds to minutes.

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Containers include a full guest operating system

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Containers provide stronger isolation than VMs

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Containers require a hypervisor to run