KCNA Practice Test 14 — 15 Questions

Question 1

Which THREE of the following are valid ways to create a Kubernetes resource using kubectl?

Accepted Answer

kubectl run nginx --image=nginx. `kubectl run nginx --image=nginx` creates a Pod imperatively, which is a valid way to create a Kubernetes resource directly from the command line without a manifest file. This command generates a Pod named 'nginx' using the specified container image, and it is a supported method for quick testing or ad-hoc resource creation.

Answer

kubectl exec -it pod-name -- /bin/bash

Answer

kubectl logs pod-name

Question 2

You have a Deployment named 'frontend' with 3 replicas. You want to perform a rolling update to a new container image. Which command should you use?

Accepted Answer

kubectl set image deployment/frontend container1=nginx:1.20. The `kubectl set image` command is the correct way to perform a rolling update on a Deployment. It directly updates the container image in the pod template, triggering a rolling update where the ReplicaSet gradually replaces old pods with new ones, ensuring zero downtime. Option A specifies the exact container name and new image, which matches the required syntax for a targeted update.

Answer

kubectl replace deployment frontend --image=nginx:1.20

Answer

kubectl edit deployment frontend --image=nginx:1.20

Answer

kubectl update deployment frontend --image=v2

Question 3

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 4

A pod is running but you need to view the contents of a file '/var/log/app.log' inside the container to debug an issue. Which kubectl command allows you to do this without modifying the pod?

Accepted Answer

kubectl exec pod-name -- cat /var/log/app.log. `kubectl exec pod-name -- cat /var/log/app.log` runs the `cat` command inside the container without modifying the pod or its state. This allows you to view the file contents directly from the container's filesystem, which is essential for debugging when the application logs are not written to stdout/stderr and thus not accessible via `kubectl logs`.

Answer

kubectl logs pod-name -c container-name --tail=100

Answer

kubectl cp pod-name:/var/log/app.log -

Answer

kubectl attach pod-name

Question 5

You need to ensure that a pod runs on a node with SSD storage. How can you achieve this?

Accepted Answer

Use node affinity with requiredDuringSchedulingIgnoredDuringExecution. Node affinity with `requiredDuringSchedulingIgnoredDuringExecution` is the correct approach because it allows you to specify a hard constraint that the pod must be scheduled on a node with a specific label (e.g., `disk=ssd`). This ensures the pod runs only on nodes that have SSD storage, as the scheduler enforces this rule during pod placement.

Answer

Use nodeSelector with a label that matches nodes having SSDs

Answer

Use a taint on nodes without SSDs and a toleration on the pod

Answer

Use pod anti-affinity to avoid nodes without SSDs

Question 6

Which Kubernetes component is responsible for maintaining the desired state of the cluster by running controllers?

Accepted Answer

kube-controller-manager. The kube-controller-manager is the component that runs controller processes, which are control loops that watch the shared state of the cluster through the kube-apiserver and make changes to drive the current state toward the desired state. It bundles together controllers such as the Node Controller, Replication Controller, and Endpoint Controller, each responsible for specific aspects of cluster state management.

Answer

kube-apiserver

Answer

kube-scheduler

Answer

etcd

Question 7

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 8

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

Accepted Answer

Services can be deployed independently. Microservices architecture is defined by the ability to deploy each service independently without affecting other services. This independence enables teams to update, scale, and roll back individual components, which is a core principle of container orchestration platforms like Kubernetes that manage these services as separate units.

Answer

All services share the same database

Answer

The entire application is deployed as a single unit

Answer

Services are tightly coupled

Question 9

Which TWO are pillars of observability? (Select two.)

Accepted Answer

Logs. Logs and Metrics are two of the three pillars of observability (alongside Traces). Logs provide immutable, timestamped records of discrete events, while Metrics are numeric aggregations of data over time (e.g., Prometheus counters, histograms). Together they form the foundation for understanding system behavior in cloud-native environments.

Answer

SLIs

Answer

Alerting

Answer

Dashboards

Question 10

A user wants to ensure that a pod is automatically restarted if its main process crashes. Which Kubernetes controller should they use?

Accepted Answer

Deployment. A Deployment is the correct controller because it manages a ReplicaSet, which ensures a specified number of pod replicas are running at all times. If the main process in a pod crashes, the ReplicaSet detects the pod failure (via the kubelet's liveness probe or the pod's phase becoming 'Failed') and automatically creates a new pod to replace it, thereby restarting the application. This self-healing behavior is a core feature of Deployments, making them ideal for stateless applications that need continuous availability.

Answer

Job

Answer

DaemonSet

Answer

CronJob

Question 11

What is a key benefit of using containers over virtual machines for application deployment?

Accepted Answer

Containers are more lightweight and start faster than VMs. Containers share the host OS kernel and run as isolated processes, requiring no separate guest OS per instance. This makes them significantly more lightweight and faster to start than VMs, which must boot a full guest OS. For application deployment, this translates to higher density, lower resource overhead, and near-instant startup times.

Answer

Containers can only run on Linux

Answer

Containers require a hypervisor to run

Answer

Containers provide stronger isolation than VMs

Question 12

A pod is in the 'Pending' state. Which of the following is a likely cause?

Accepted Answer

No node has sufficient resources to run the pod. A pod enters the 'Pending' state when it has been accepted by the API server but cannot be scheduled onto a node. The most common cause is insufficient cluster resources (CPU, memory, or ephemeral storage) on any available node to satisfy the pod's resource requests. The Kubernetes scheduler continuously evaluates node resource availability and will leave the pod in Pending until a suitable node is found or the request times out.

Answer

The liveness probe is failing

Answer

The container image is not found in the registry

Answer

The container exited with OOMKilled

Question 13

Which THREE of the following are valid fields in a Kubernetes Deployment spec (apps/v1)?

Accepted Answer

replicas. The `replicas` field is a standard part of the Deployment spec under `apps/v1`, defining the desired number of Pod replicas. Option B is correct because the `template` field is mandatory, containing the Pod template that describes the Pods to be created. Option C is correct because the `selector` field is required to match the Pods managed by the Deployment, ensuring the ReplicaSet controls the correct Pods.

Answer

containers

Answer

nodeName

Question 14

A team uses Argo Rollouts for progressive delivery. They configure a canary rollout with a traffic split of 20% to the new version. After verification, the rollout automatically increases traffic to 100%. Which Argo Rollout manifest field controls this gradual traffic increase?

Accepted Answer

strategy.canary.steps. The steps field in an Argo Rollout defines the sequence of canary steps, including traffic percentages. Option B (strategy.canary.steps) is correct. Option A (strategy.canary.trafficRouting) configures how traffic routing is done (e.g., with a service mesh). Option C (spec.replicas) sets the total replicas. Option D (template.spec.containers) defines containers.

Answer

strategy.canary.trafficRouting

Answer

template.spec.containers

Answer

spec.replicas

Question 15

Which of the following best describes the 12-factor app methodology's approach to configuration?

Accepted Answer

Configuration is stored in environment variables. The 12-factor app methodology states that configuration should be stored in environment variables to separate config from code.

Answer

Configuration is hardcoded in the application code

Answer

Configuration is stored in a database and accessed at runtime

Answer

Configuration is managed by a configuration server