KCNA Kubernetes Fundamentals Practice Test 14 — 15 Questions

Question 1

A Pod is in 'CrashLoopBackOff' state. You run 'kubectl logs <pod>' and see an error that the application cannot bind to port 8080 because the port is already in use. What is the most likely cause?

Accepted Answer

Another process inside the container is already using port 8080. The 'CrashLoopBackOff' state indicates the container repeatedly starts, fails, and is restarted by the kubelet. The error message 'port is already in use' means the application inside the container cannot bind to port 8080 because another process within the same container's network namespace is already listening on that port. This is a classic application-level conflict, not a Kubernetes configuration issue.

Answer

The container's health check is misconfigured

Answer

The container runtime is not installed

Answer

The Pod's resource limits are too low

Question 2

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

Answer

kubectl list pods

Answer

kubectl show pods

Question 3

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 4

A Deployment has a strategy of RollingUpdate with maxSurge=1 and maxUnavailable=0. The Deployment manages 3 replicas. The image is updated. What happens during the update?

Accepted Answer

One new Pod is created, and once it is ready, one old Pod is terminated. This repeats until all Pods are updated.. The RollingUpdate strategy with maxSurge=1 and maxUnavailable=0 ensures that during the update, exactly one new Pod is created above the desired replica count (surge of 1) while keeping all existing Pods running (maxUnavailable=0). Once the new Pod reaches the Ready state, one old Pod is terminated, maintaining the desired 3 replicas throughout the process. This cycle repeats until all Pods are updated, guaranteeing zero downtime.

Answer

All 3 new Pods are created, and then the old ones are terminated all at once

Answer

All 3 old Pods are terminated simultaneously before new ones start

Answer

The update fails because maxUnavailable cannot be 0

Question 5

Which component runs on each worker node and ensures that containers are running as specified in the Pod spec?

Accepted Answer

kubelet. The kubelet is the primary node agent that runs on every worker node in a Kubernetes cluster. It receives PodSpec definitions (via the API server or a file) and ensures that the containers described in those PodSpecs are running and healthy. It does this by interacting with the container runtime (e.g., containerd or CRI-O) to start, stop, and monitor containers, and it reports the node and pod status back to the control plane.

Answer

kube-proxy

Answer

kube-scheduler

Answer

kube-controller-manager

Question 6

Which TWO of the following are true about Kubernetes Services? (Select 2)

Accepted Answer

Services can distribute traffic across Pods using labels and selectors.. Option B is correct because a Kubernetes Service uses label selectors to identify the set of backing Pods (typically via Endpoints/EndpointSlices) and load-balances traffic across them, providing a single access point regardless of how many Pod replicas exist. Option D is correct because a Service is assigned a stable virtual IP (ClusterIP) and a DNS name (e.g., my-svc.my-namespace.svc.cluster.local) that remain constant even as the underlying Pods are created, deleted, or rescheduled with new IPs. Option A is wrong because replication and scaling are handled by controllers such as ReplicaSets or Deployments, not by Services. Option C is wrong because Services can also be exposed externally via NodePort, LoadBalancer, or ExternalName types, not only internally. Option E is wrong because persistent storage is provided by PersistentVolumes and PersistentVolumeClaims, which are independent of Services.

Answer

Services automatically handle Pod replication and scaling.

Answer

Services can only expose Pods internally within the cluster.

Answer

Services are required for Pods to have persistent storage.

Question 7

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.. Option B is correct because StatefulSets give each Pod a stable, unique network identity via a headless Service and predictable DNS names (pod-0, pod-1, etc.) that persist across rescheduling, which Deployments do not guarantee. Option D is correct because StatefulSets use volumeClaimTemplates to bind a dedicated PersistentVolumeClaim to each Pod, so each replica keeps its own persistent storage across rescheduling, unlike a Deployment where all replicas typically share or lack per-Pod PVCs. Option E is correct because StatefulSets provide ordered, graceful deployment and scaling (0..N-1) and reverse-order termination with graceful shutdown, which is essential for clustered stateful apps. Option A is not a reason to use a StatefulSet because unordered, rapid scaling is exactly what Deployments handle well. Option C is not a reason because stateless, arbitrarily replicable workloads are the canonical use case for Deployments, not StatefulSets.

Answer

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

Answer

The application is stateless and can be replicated arbitrarily.

Question 8

Which TWO of the following components are part of the Kubernetes control plane? (Select 2)

Accepted Answer

kube-apiserver. The Kubernetes control plane consists of components that make global cluster decisions and store cluster state. Option B, kube-apiserver, is correct because it is the central management endpoint that exposes the Kubernetes API, validates and processes REST requests, and is the front end through which all other components communicate. Option D, etcd, is correct because it is the consistent, highly-available key-value store that persists all cluster data, including object specs and state, and is the backing store for the API server. The unmarked options are node-level components, not control plane components: the container runtime (A) executes containers on each node, kubelet (C) is the node agent that manages pods and containers on a node, and kube-proxy (E) implements Service networking rules on each node.

Answer

container runtime

Answer

kubelet

Answer

kube-proxy

Question 9

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

Answer

kube-scheduler

Answer

kube-apiserver

Question 10

What is the purpose of a Service in Kubernetes?

Accepted Answer

To expose a set of pods as a network service with a stable endpoint. A Service in Kubernetes provides a stable network endpoint (IP address and DNS name) to access a set of Pods, which are ephemeral and can be created or destroyed dynamically. It decouples the client from the Pods' IPs by using label selectors to route traffic, enabling reliable communication within the cluster or externally. This is defined in the Kubernetes API as a Service resource, with types like ClusterIP, NodePort, and LoadBalancer.

Answer

To provide persistent storage volumes

Answer

To manage rolling updates of pods

Answer

To store configuration data as key-value pairs

Question 11

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

Answer

kubectl describe pod <pod-name>

Answer

kubectl get logs <pod-name>

Question 12

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

Answer

The container image name is misspelled

Answer

The ReplicaSet controller is not running

Question 13

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 as plain text with no encoding or encryption, and are designed for configuration that does not require confidentiality.

Answer

Secret

Answer

Annotation

Answer

Volume

Question 14

A pod is stuck in 'Pending' state. After running 'kubectl describe pod', you see the event: '0/3 nodes are available: 3 Insufficient cpu'. What is the most likely cause?

Accepted Answer

The pod's CPU request exceeds the available CPU on all nodes. The pod is stuck in 'Pending' state because the Kubernetes scheduler cannot find a node that satisfies the pod's resource requirements. The event '0/3 nodes are available: 3 Insufficient cpu' explicitly indicates that every node in the cluster lacks sufficient allocatable CPU capacity to meet the pod's CPU request. This means the sum of CPU requests across all pods on each node, plus the new pod's request, exceeds the node's CPU capacity, causing the scheduler to leave the pod unscheduled.

Answer

The pod is exceeding its memory limit

Answer

The network plugin is not installed

Answer

The container image is too large

Question 15

Which field in a Deployment YAML specifies the number of pod replicas?

Accepted Answer

spec.replicas. In a Kubernetes Deployment YAML, the `spec.replicas` field directly defines the desired number of pod replicas that the Deployment controller should maintain. This is a top-level field under the Deployment spec, not nested under `template.spec`, because the replica count is a property of the Deployment itself, not of the Pod template.

Answer

spec.template.spec.replicas

Answer

spec.replicaCount

Answer

spec.selector.matchLabels