KCNA Practice Test 42 — 15 Questions

Question 1

A Deployment named 'web-app' is configured with replicas: 3. You update the container image. Which Kubernetes object directly manages the pods during the rolling update?

Accepted Answer

ReplicaSet. When a Deployment is updated (e.g., container image change), it creates a new ReplicaSet to manage the new pods and scales down the old ReplicaSet. The ReplicaSet is the Kubernetes object that directly owns and manages the pods during the rolling update, ensuring the desired number of replicas are running at each step.

Answer

StatefulSet

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DaemonSet

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Job

Question 2

In GitOps, what is the role of a tool like ArgoCD?

Accepted Answer

To automatically apply changes from a Git repository to a Kubernetes cluster. ArgoCD is a declarative GitOps continuous delivery tool for Kubernetes. It continuously monitors a Git repository that stores the desired state of applications (manifests, Helm charts, Kustomize) and compares it to the live state in the cluster. When a difference is detected, ArgoCD automatically syncs the cluster to match the Git repository, thereby applying changes. This pull-based model ensures that Git is the single source of truth for both application and infrastructure configurations.

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To monitor application performance

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To create Docker images from source code

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To manage container registries

Question 3

You run 'kubectl get pods' and see a pod in 'Pending' state for over 5 minutes. You describe the pod and see '0/1 nodes are available: 1 Insufficient memory'. What is the most likely cause?

Accepted Answer

The pod's memory request is larger than any node's allocatable memory. The '0/1 nodes are available: 1 Insufficient memory' message indicates that the Kubernetes scheduler could not place the pod because no node has enough allocatable memory to satisfy the pod's memory request. Option B is correct because the pod's memory request exceeds the available memory on any node, causing the pod to remain in Pending state indefinitely until sufficient resources become available.

Answer

The container image is too large

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The pod has a liveness probe that is failing

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The kubelet on the node is not running

Question 4

Which Kubernetes component is the primary entry point for all administrative tasks and API requests?

Accepted Answer

kube-apiserver. The kube-apiserver is the front-end of the Kubernetes control plane and the sole entry point for all administrative tasks and API requests. It validates and processes RESTful API calls (using JSON/YAML over HTTP/HTTPS) before persisting state to etcd or delegating work to other controllers. Without the API server, no kubectl command, automation script, or internal component can interact with the cluster.

Answer

kube-controller-manager

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etcd

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kube-scheduler

Question 5

Which two of the following are responsibilities of the kubelet? (Select TWO.)

Accepted Answer

Reporting the node's status to the control plane. Option A is correct because the kubelet runs on each node and periodically reports node status (including conditions, capacity, and allocatable resources) to the control plane via the API server, typically through NodeStatus updates. Option E is correct because the kubelet acts as the node agent that watches PodSpecs assigned to its node and ensures the specified containers are running and healthy, restarting them as needed via the container runtime. Option B is incorrect because implementing network rules for services is the job of kube-proxy (using iptables/IPVS), not the kubelet. Option C is incorrect because assigning pods to nodes is performed by the kube-scheduler, which selects a node based on resource availability and constraints. Option D is incorrect because storing cluster state in a key-value store is the role of etcd, the cluster's backing datastore.

Answer

Implementing network rules for services

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Assigning pods to nodes based on resource availability

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Storing cluster state in a key-value store

Question 6

Which command is used to view detailed information about a specific pod, including events and conditions?

Accepted Answer

kubectl describe pod. The `kubectl describe pod` command retrieves detailed information about a specific pod, including its current state, metadata, labels, annotations, container details, resource limits, and a chronological list of events and conditions (e.g., PodScheduled, Initialized, Ready, ContainersReady). This makes it the correct tool for viewing comprehensive pod status and lifecycle events.

Answer

kubectl logs pod

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kubectl exec pod

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kubectl get pod

Question 7

What is the concept of 'immutable infrastructure' as applied to Kubernetes?

Accepted Answer

Pods are replaced with new versions rather than being modified. Immutable infrastructure in Kubernetes means that instead of modifying running Pods or their containers (e.g., patching a binary or updating a config file in place), you replace the entire Pod with a new version. This is enforced by Kubernetes' declarative model: when you update a Deployment's Pod template, the controller creates new Pods with the new image and terminates the old ones. This ensures consistency, repeatability, and eliminates configuration drift, as every change results in a fresh, identical instance from the same image.

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Configuration is stored in environment variables only

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Containers are rebuilt from the same base image every time

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Infrastructure components are never replaced; they are updated in place

Question 8

Which practice is a key principle of cloud-native architecture?

Accepted Answer

Automated CI/CD pipelines. Automated CI/CD pipelines are a key principle of cloud-native architecture because they enable rapid, reliable, and repeatable delivery of microservices. By automating build, test, and deployment stages, teams can achieve continuous integration and continuous delivery, which aligns with the cloud-native goals of agility, scalability, and resilience. This automation reduces human error and accelerates the feedback loop, essential for managing distributed systems in dynamic cloud environments.

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Manual configuration management

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Tight coupling of services

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Preferring stateful applications over stateless

Question 9

Which TWO of the following are characteristics of a microservices architecture? (Select 2)

Accepted Answer

Independent deployment of services. Option A (Independent deployment of services) is correct because microservices are built as separately deployable units, so a change to one service can be built, tested, and released without redeploying the entire application. Option C (Loose coupling between services) is correct because microservices interact through well-defined interfaces (typically REST, gRPC, or messaging) and minimize dependencies on each other's internal implementation, allowing them to evolve independently. Option B (Tight coupling between services) is incorrect because tight coupling is characteristic of monolithic designs, where components are highly interdependent. Option D (Monolithic codebase) is incorrect because microservices decompose functionality into multiple small, independently managed codebases rather than one unified codebase. Option E (Shared database for all services) is incorrect because microservices generally favor database-per-service to avoid coupling through shared schemas and to preserve service autonomy.

Answer

Tight coupling between services

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Monolithic codebase

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Shared database for all services

Question 10

Which of the following kubectl commands would you use to apply a manifest file and also save it for later updates?

Accepted Answer

kubectl apply -f manifest.yaml. `kubectl apply` uses a declarative approach: it creates the resource if it doesn't exist and updates it if it does, while also storing the last-applied configuration as an annotation (`kubectl.kubernetes.io/last-applied-configuration`). This allows future `apply` calls to perform a three-way merge diff (current live state, last-applied config, and new manifest) to intelligently update the resource, making it the standard for managing manifests that need ongoing updates.

Answer

kubectl create -f manifest.yaml

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kubectl patch -f manifest.yaml

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kubectl replace -f manifest.yaml

Question 11

A company wants to ensure that a database pod runs on a node with SSD storage. How should this be achieved?

Accepted Answer

Label SSD nodes with 'disk=ssd' and add a nodeSelector to the pod. NodeSelector is a field in the Pod spec that constrains which nodes the Pod can be scheduled on, based on node labels. By labeling nodes with SSD storage as 'disk=ssd' and adding a nodeSelector with that label to the Pod, Kubernetes will only schedule the Pod on nodes that have the matching label, ensuring it runs on SSD storage.

Answer

Set a resource request for local SSD storage in the pod spec

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Use pod anti-affinity to avoid non-SSD nodes

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Add a taint to nodes without SSDs and a toleration to the pod

Question 12

A pod is in CrashLoopBackOff. You check the logs and see 'Error: container process not found'. What is the most likely cause?

Accepted Answer

The container's entrypoint or command is incorrect. The container's entrypoint or command may be misconfigured, causing the container to exit immediately.

Answer

The pod has insufficient memory

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The liveness probe is misconfigured

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The container image is missing

Question 13

A Deployment is configured with 'strategy.type: RollingUpdate' and 'strategy.rollingUpdate.maxUnavailable: 0'. What is the effect during a rolling update?

Accepted Answer

No pod will be terminated until a new pod is ready. Setting `maxUnavailable: 0` means the Deployment controller will not terminate any existing pod until a new pod is fully ready. This ensures zero disruption to the application during the rolling update, as the controller waits for the new pod to pass its readiness probe before scaling down the old ReplicaSet.

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The update will fail because maxUnavailable must be at least 1

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The update will not proceed until at least one new pod is ready

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The update will proceed without any downtime

Question 14

Which of the following best describes 'Infrastructure as Code' (IaC)?

Accepted Answer

Defining infrastructure resources in a declarative configuration file. IaC is fundamentally about declaring the desired end state of infrastructure in machine-readable configuration files (Terraform HCL, CloudFormation YAML, Kubernetes manifests) and letting a tool reconcile reality to match that declaration. Option D captures this declarative model, which is the defining characteristic of modern IaC. The key distinction is that the file describes *what* the infrastructure should look like, not the step-by-step *how*.

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Manually configuring servers via SSH

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Using a scripting language to automate tasks

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Running containers on a Kubernetes cluster

Question 15

You have a YAML manifest for a Deployment with 'apiVersion: extensions/v1beta1'. When you run 'kubectl apply -f manifest.yaml', you get an error. What is the most likely cause?

Accepted Answer

The apiVersion is deprecated and not supported. `extensions/v1beta1` was deprecated starting in Kubernetes 1.16 and removed entirely in Kubernetes 1.22. Running `kubectl apply` against a manifest with this apiVersion will result in an error because the API group and version are no longer recognized by the API server. The correct apiVersion for Deployments is `apps/v1`, which is the stable and currently supported version.

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The namespace does not exist

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The YAML syntax is invalid

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The 'kind' field is misspelled