KCNA Kubernetes Fundamentals Practice Test 3 — 15 Questions

Question 1

A Deployment named 'web-app' has been running with 3 replicas. After a configuration change, you notice that only 2 pods are ready. You run 'kubectl describe deployment web-app' and see 'Replicas: 3 desired | 3 total | 3 up-to-date | 2 available'. What is the most likely cause?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

The pods have a failing readiness probe. The key detail is that 3 pods are desired, 3 are up-to-date, but only 2 are available. This indicates the pods are running but not passing their readiness probes, so they are not included in the Service's endpoints. A failing readiness probe prevents traffic from being routed to a pod, even if it is otherwise healthy, which matches the symptom of fewer available pods than desired.

Answer

The Deployment's resource requests exceed node capacity

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The Service selector does not match the pod labels

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The kubelet on one node is not functioning

Question 2

You want to run a batch job that processes a queue and then terminates. Which Kubernetes resource should you use?

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 they successfully finish executing a specific workload, making it the correct choice for processing a queue and then exiting.

Answer

Deployment

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CronJob

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DaemonSet

Question 3

A pod is stuck in the 'Pending' state. Which command would you use to get more details about why the pod cannot be scheduled?

Accepted Answer

kubectl describe pod . `kubectl describe pod ` provides detailed event logs and status information, including scheduler decisions, resource constraints, and node conditions that explain why a pod remains in 'Pending' state. The 'Pending' state typically indicates the pod has not been scheduled, and `kubectl describe` surfaces the exact reason, such as insufficient CPU/memory, persistent volume claims not bound, or node selector mismatches.

Answer

kubectl logs <pod-name>

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kubectl exec -it <pod-name> -- sh

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kubectl get pod <pod-name> -o yaml

Question 4

Which THREE of the following are valid ways to pass configuration data to a container in a pod? (Select 3)

Accepted Answer

Setting environment variables directly in the pod spec. Environment variables can be defined directly in the pod spec under the `env` field, allowing configuration data to be passed as key-value pairs. This is a native Kubernetes mechanism that does not require external objects like ConfigMaps or Secrets, making it a valid and straightforward way to inject configuration into a container at runtime.

Answer

Modifying the container image after deployment

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Using a PersistentVolumeClaim to store configuration

Question 5

Which TWO statements are true about Kubernetes namespaces? (Select 2)

Accepted Answer

Resource quotas can be applied to a namespace to limit resource usage. Kubernetes allows administrators to define ResourceQuota objects per namespace, which can constrain aggregate resource consumption (e.g., CPU, memory, persistent volume claims) across all pods in that namespace. This is enforced by the API server admission controller, preventing any single namespace from exhausting cluster resources.

Answer

All Kubernetes resources are namespaced

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Namespaces provide network isolation by default

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Deleting a namespace automatically deletes all resources in it, including cluster-scoped resources

Question 6

You need to update a Deployment's container image from nginx:1.14 to nginx:1.16 and ensure zero downtime. Which kubectl command should you use?

Accepted Answer

kubectl set image deployment/my-deployment nginx=nginx:1.16. `kubectl set image` directly updates the container image in the Deployment's pod template, triggering a rolling update. Kubernetes Deployments handle zero-downtime updates by default via a rolling update strategy, which gradually replaces old pods with new ones while keeping the service available.

Answer

kubectl patch deployment my-deployment -p '{"spec":{"template":{"spec":{"containers":[{"name":"nginx","image":"nginx:1.16"}]}}}}'

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kubectl edit deployment my-deployment --image=nginx:1.16

Answer

kubectl update deployment my-deployment --image=nginx:1.16

Question 7

A Pod has been in 'Pending' state for an unusual amount of time. Which of the following is a likely cause?

Accepted Answer

The cluster does not have enough resources to schedule the Pod. A Pod stuck in 'Pending' state indicates that the Pod has been accepted by the API server but has not been scheduled to a node. The most common cause is insufficient cluster resources (CPU, memory, or ephemeral storage) across all nodes, preventing the scheduler from finding a suitable node that meets the Pod's resource requests. The scheduler continuously evaluates nodes using predicates and priorities, and if no node passes the predicates (e.g., NodeResourcesFit), the Pod remains Pending.

Answer

The container image is invalid

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The Pod's liveness probe is failing

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The Service pointing to the Pod is misconfigured

Question 8

Which Kubernetes object provides stable network endpoints and load balancing for a set of Pods?

Accepted Answer

Service. A Service is the Kubernetes abstraction that defines a logical set of Pods and a policy for accessing them, providing a stable IP address and DNS name that remains constant even as Pods are created or destroyed. Services use label selectors to identify target Pods and perform Layer 4 (TCP/UDP) load balancing across them, either via iptables, IPVS, or eBPF rules in kube-proxy.

Answer

NetworkPolicy

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Deployment

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Ingress

Question 9

Which command would you use to view the current state of all Pods in the default namespace?

Accepted Answer

kubectl get pods. The `kubectl get pods` command retrieves and displays the current state of all Pods in the default namespace. It is the standard imperative command for listing Kubernetes resources, showing key fields like NAME, READY, STATUS, RESTARTS, and AGE.

Answer

kubectl describe pods

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kubectl list pods

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kubectl show pods

Question 10

You want to isolate a team's workloads within a Kubernetes cluster so that they cannot see or access resources from other teams. Which feature should you use?

Accepted Answer

Namespaces. Namespaces are the Kubernetes abstraction that provides a logical partition of the cluster, enabling multi-tenancy by isolating workloads, resources, and access controls. By default, RBAC policies and network policies can be scoped to a namespace, preventing teams from seeing or accessing resources in other namespaces.

Answer

Annotations

Answer

Labels and selectors

Answer

Resource quotas

Question 11

Which THREE of the following are valid reasons to use a StatefulSet instead of a Deployment? (Select 3)

Accepted Answer

The application requires stable unique network identifiers that persist across rescheduling.. StatefulSets provide stable, unique network identities (e.g., pod-0.svc.cluster.local) that persist across rescheduling, which is essential for applications like databases that rely on hostname-based discovery. Deployments assign random pod names and IPs, making them unsuitable for stateful workloads requiring consistent identity.

Answer

The application needs to be scaled up and down quickly without regard to order.

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The application is stateless and can be replicated arbitrarily.

Question 12

Which Kubernetes component is responsible for ensuring that the desired number of pod replicas is running in the cluster?

Accepted Answer

kube-controller-manager. The kube-controller-manager runs controller processes, including the Replication Controller, which is responsible for ensuring that the desired number of pod replicas are running at all times. It watches the current state via the API server and takes corrective actions (e.g., creating or deleting pods) to match the desired replica count defined in the ReplicaSet or Deployment.

Answer

kubelet

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kube-scheduler

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kube-apiserver

Question 13

Which kubectl command would you use to view the logs of a specific pod?

Accepted Answer

kubectl logs . `kubectl logs ` is the standard Kubernetes command to retrieve logs from a specified pod. This command fetches the container's stdout and stderr streams, which are captured by the kubelet and stored as log files on the node. It directly accesses the pod's log output without requiring any additional flags or subcommands.

Answer

kubectl exec <pod-name> -- logs

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kubectl describe pod <pod-name>

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kubectl get logs <pod-name>

Question 14

A user creates a Deployment with 'replicas: 3'. After applying the manifest, only 2 pods are running. What is the most likely cause?

Accepted Answer

There is insufficient node capacity to schedule the third pod. The most likely cause is insufficient node capacity, as the scheduler cannot place the third pod due to resource constraints (CPU, memory, or other limits). The Deployment controller creates a ReplicaSet, which instructs the scheduler to place pods; if nodes lack sufficient allocatable resources, pods remain in Pending state. This is a common scenario when cluster resources are exhausted.

Answer

The Deployment's YAML had a syntax error

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The container image name is misspelled

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The ReplicaSet controller is not running

Question 15

Which Kubernetes object is used to store non-sensitive configuration data that can be consumed by pods?

Accepted Answer

ConfigMap. ConfigMap is the correct Kubernetes object for storing non-sensitive configuration data, such as environment variables, command-line arguments, or configuration files, that can be consumed by pods. Unlike Secrets, ConfigMaps store data in plain text (base64-encoded only for transport) and are designed for configuration that does not require encryption.

Answer

Secret

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Annotation

Answer

Volume