KCNA Practice Test 37 — 15 Questions

Question 1

Which TWO components are part of the Kubernetes control plane?

Accepted Answer

kube-apiserver. The Kubernetes control plane manages the cluster's state and scheduling decisions. The kube-apiserver (C) is the front-end for the control plane, exposing the Kubernetes API, while etcd (D) is the distributed key-value store that holds all cluster data, including configuration and state. Both are essential control plane components.

Answer

container runtime

Answer

kubelet

Answer

kube-proxy

Question 2

Which TWO statements are true about Kustomize? (Choose 2)

Accepted Answer

It supports patching Kubernetes resources via strategic merge patches or JSON patches.. Kustomize uses a base and overlay model to manage environment-specific configurations (D). It supports patching Kubernetes resources via strategic merge patches or JSON patches (A). Kustomize does not use Go templating; it is template-free. It does not handle canary traffic routing, which is typically done by service mesh or deployment tools. It does not package or deploy Helm charts natively.

Answer

It automatically handles canary traffic routing.

Answer

It relies on Go templating to generate Kubernetes manifests.

Answer

It can be used to package and deploy Helm charts.

Question 3

A user wants to run a one-time batch job that runs to completion. Which Kubernetes resource should they use?

Accepted Answer

Job. A Kubernetes Job is the correct resource for a one-time batch job that runs to completion. Unlike controllers designed for long-running processes, a Job creates one or more Pods and ensures they successfully terminate, making it ideal for finite tasks like data processing or backups.

Answer

StatefulSet

Answer

DaemonSet

Answer

Deployment

Question 4

Which TWO components are part of the Kubernetes control plane? (Select exactly two.)

Accepted Answer

kube-apiserver. The kube-apiserver is the front-end of the Kubernetes control plane, exposing the Kubernetes API for all cluster operations. The kube-scheduler is responsible for assigning newly created pods to nodes based on resource availability and policy constraints. Both are essential control plane components that manage cluster state and scheduling decisions.

Answer

kube-proxy

Answer

kubelet

Answer

container runtime

Question 5

A user reports that they cannot connect to a database service named 'db-service' from another pod in the same namespace. The service selector matches the database pod's labels. Which command would you run FIRST to troubleshoot the service's endpoints?

Accepted Answer

kubectl get endpoints db-service. `kubectl get endpoints db-service` directly shows whether the service has any endpoints (i.e., pod IPs) associated with it. If the endpoints list is empty, it indicates that the service's label selector is not matching any pods, which is the most common cause of connectivity failure. This is the fastest way to verify the fundamental prerequisite for service-to-pod traffic.

Answer

kubectl describe pod db-service

Answer

kubectl exec -it <some-pod> -- curl db-service

Answer

kubectl logs db-service

Question 6

What is the primary purpose of the CNCF (Cloud Native Computing Foundation)?

Accepted Answer

To host and nurture open-source cloud-native projects. The CNCF's primary purpose is to host and nurture open-source cloud-native projects, such as Kubernetes, Prometheus, and Envoy, by providing governance, community support, and a neutral home for their development. It does not provide cloud infrastructure services itself, nor does it develop proprietary technologies; instead, it fosters an ecosystem of interoperable, vendor-neutral projects. The CNCF also manages the Cloud Native Landscape and defines standards like the Open Container Initiative (OCI) for container runtimes and images, but its scope extends far beyond just standardizing container runtimes.

Answer

To provide cloud infrastructure services

Answer

To develop proprietary cloud technologies

Answer

To standardize container runtimes only

Question 7

A user reports that their application's DNS resolution is failing for a Service named 'my-service' in the same namespace. They are able to reach the Service by its cluster IP. Which of the following is the most likely cause?

Accepted Answer

The CoreDNS pod is not running or misconfigured. DNS resolution for a Service in the same namespace relies on CoreDNS, which is the cluster DNS provider in Kubernetes. If CoreDNS is not running or misconfigured, DNS queries for the Service name (e.g., 'my-service') will fail, even though the Service is reachable via its cluster IP. The user's ability to reach the Service by IP confirms that kube-proxy and networking are functional, isolating the issue to DNS resolution.

Answer

The application container is using an incorrect DNS policy

Answer

The kube-proxy is misconfigured on the node

Answer

The Service is of type ExternalName

Question 8

A Service of type ClusterIP is created. What is the default behavior of this Service?

Accepted Answer

It exposes the Service on a cluster-internal IP. A ClusterIP Service is the default Kubernetes Service type, which assigns a virtual IP address reachable only within the cluster. Traffic sent to this IP is load-balanced across the Pods selected by the Service's label selector, using iptables or IPVS rules. No external access is provided unless an Ingress or other mechanism is explicitly configured.

Answer

It exposes the Service externally via a cloud load balancer

Answer

It exposes the Service on a static port on each node

Answer

It routes traffic to Pods based on external DNS names

Question 9

Which component runs on every Kubernetes node and ensures that the containers in a pod are running?

Accepted Answer

kubelet. The kubelet is the primary node agent that runs on every Kubernetes node. It receives PodSpec definitions from the API server and ensures that the containers described in those PodSpecs are running and healthy. It continuously monitors container status and takes corrective actions, such as restarting containers that have failed, making it the correct answer.

Answer

kube-proxy

Answer

kube-scheduler

Answer

container runtime

Question 10

A user runs 'kubectl create deployment my-deploy --image=nginx' and then wants to scale the deployment to 5 replicas. Which command should they use?

Accepted Answer

kubectl scale deployment my-deploy --replicas=5. `kubectl scale` is the dedicated imperative command to change the replica count of a deployment. It directly updates the `spec.replicas` field in the deployment's desired state, and the deployment controller then adjusts the ReplicaSet and Pods accordingly. This is the simplest and most direct way to scale a deployment without modifying a YAML file or using an editor.

Answer

kubectl apply -f deployment.yaml with replicas: 5

Answer

kubectl edit deployment my-deploy and change replicas to 5

Answer

kubectl patch deployment my-deploy -p '{"spec":{"replicas":5}}'

Question 11

You are troubleshooting a service that is not accessible from within the cluster. The service has a label selector that matches the pods. You run 'kubectl get endpoints myservice' and see that the ENDPOINTS column is empty. What is the most likely cause?

Accepted Answer

The service's label selector does not match any pods. The ENDPOINTS column being empty for a service indicates that the service's label selector does not match any running pods. Kubernetes uses the label selector to dynamically populate the endpoints list; if no pods match, the service has no backends to forward traffic to, making it inaccessible from within the cluster.

Answer

The kube-proxy is not running

Answer

The service is in a different namespace

Answer

The service type is LoadBalancer and no external load balancer is provisioned

Question 12

A pod is stuck in 'Pending' state. You run 'kubectl describe pod mypod' and see the event '0/4 nodes are available: 4 Insufficient cpu'. What is the most likely cause?

Accepted Answer

None of the nodes have enough CPU resources to satisfy the pod's request. The '0/4 nodes are available: 4 Insufficient cpu' event directly indicates that the Kubernetes scheduler attempted to place the pod on each of the four nodes but found that none had enough allocatable CPU capacity to satisfy the pod's CPU request (specified in the container's `resources.requests.cpu`). This causes the pod to remain in 'Pending' state because the scheduler cannot find a feasible node.

Answer

The pod has exceeded its memory limit

Answer

The pod's image pull is failing

Answer

The pod's liveness probe is failing

Question 13

Which TWO of the following are valid methods to expose a set of pods to external traffic in Kubernetes?

Accepted Answer

LoadBalancer Service. A LoadBalancer Service is a valid method to expose pods to external traffic because it provisions an external load balancer (e.g., AWS ELB, GCP LB) that assigns a public IP address, routing external traffic to the Service's ClusterIP and then to the pods. This is a standard Kubernetes Service type defined in the ServiceSpec, making it correct for external exposure.

Answer

Headless Service

Answer

ClusterIP Service

Answer

Ingress

Question 14

You have a Deployment with 3 replicas. You need to perform a rolling update with 2 extra pods during the update and ensure that only 1 pod is unavailable at any time. Which update strategy configuration achieves this?

Accepted Answer

maxSurge: 2, maxUnavailable: 1. It sets maxSurge to 2 (allowing up to 2 extra pods above the desired 3, for a total of 5 pods during the update) and maxUnavailable to 1 (ensuring at most 1 pod is unavailable at any time). This satisfies the requirement of having 2 extra pods during the update while keeping only 1 pod unavailable.

Answer

maxSurge: 1, maxUnavailable: 2

Answer

maxSurge: 0, maxUnavailable: 2

Answer

maxSurge: 3, maxUnavailable: 0

Question 15

In PromQL, which function would you use to calculate the per-second rate of increase of a counter over a specified time window?

Accepted Answer

rate(). The rate() function calculates the per-second average rate of increase of a counter over a time range.

Answer

delta()

Answer

avg_over_time()

Answer

increase()