KCNA Kubernetes Fundamentals Practice Test 27 — 15 Questions

Question 1

What is the purpose of a liveness probe in a Kubernetes pod?

Accepted Answer

To check if the application is still running; if not, restart the container. A liveness probe in Kubernetes is used to determine if a container is still running and healthy. If the probe fails, the kubelet kills the container and restarts it based on the pod's restart policy. This ensures that applications that have entered a deadlock or hung state are automatically recovered without manual intervention.

Answer

To check if the pod is scheduled on a node

Answer

To check if the container has started successfully

Answer

To check if the application is ready to serve traffic

Question 2

You create a Deployment with replicas: 3. You then scale the Deployment to 5 replicas. What is the order of operations that the Deployment controller follows?

Accepted Answer

It updates the existing ReplicaSet's replica count to 5, and the ReplicaSet creates the new pods. When you scale a Deployment, the Deployment controller updates the replica count on the existing ReplicaSet that matches the pod template. The ReplicaSet controller then observes the desired count and creates the additional pods to reach the new target. This ensures that the Deployment's rollout history and rollback capabilities remain intact.

Answer

It creates a new ReplicaSet with 5 replicas and deletes the old one

Answer

It directly creates 2 new pods without using a ReplicaSet

Answer

It creates 2 new pods immediately without modifying the existing ReplicaSet

Question 3

A developer wants to inject environment variables into a pod from a ConfigMap named 'app-config'. Which YAML snippet correctly mounts all key-value pairs from the ConfigMap as environment variables?

Accepted Answer

envFrom:
  - configMapRef:
      name: app-config. `envFrom` with a `configMapRef` injects all key-value pairs from the ConfigMap named 'app-config' as environment variables into the container. This is the standard Kubernetes method for bulk injection of ConfigMap data into environment variables, as opposed to selecting individual keys.

Answer

env:
  - name: CONFIG
    value: "$(CONFIGMAP)"

Answer

volumes:
  - name: config
    configMap:
      name: app-config
    volumeMounts:
      - name: config
        mountPath: /etc/config

Answer

env:
  - name: CONFIG
    valueFrom:
      configMapKeyRef:
        name: app-config
        key: config.yaml

Question 4

You have a Deployment with the following rollout strategy: rollingUpdate: maxSurge: 1, maxUnavailable: 0. What behavior does this configuration enforce?

Accepted Answer

The rollout will create one additional pod before terminating the old pod, ensuring zero downtime. The rolling update strategy `maxSurge: 1, maxUnavailable: 0` ensures that during the rollout, one additional pod is created above the desired replica count before any existing pod is terminated. This guarantees that the total number of available pods never drops below the desired count, achieving zero downtime. The `maxUnavailable: 0` setting prevents any pod from being taken down until a new one is ready, while `maxSurge: 1` allows one extra pod to be created temporarily.

Answer

The rollout will terminate all old pods at once and then create new ones

Answer

The rollout will create all new pods first, then delete all old pods

Answer

The rollout will terminate one old pod before creating a new one

Question 5

A user reports that they cannot connect to a Service from within the cluster. The Service is of type ClusterIP. Running 'kubectl get endpoints service-name' shows no endpoints. What is the most likely cause?

Accepted Answer

The Service's pod selector does not match any running pods. If endpoints are empty, the Service selector does not match any pods, or the pods are not ready.

Answer

The Service is not associated with a namespace

Answer

The Service is exposed on the wrong port

Answer

The kube-proxy is not running on the node

Question 6

Which TWO of the following are valid ways to assign a pod to a specific node?

Accepted Answer

nodeSelector. `nodeSelector` is a simple, built-in field in the Pod spec that matches the pod to nodes with specific labels. When you add a `nodeSelector` with a key-value pair, the scheduler only places the pod on nodes that have that exact label. This is the most straightforward way to constrain a pod to a subset of nodes.

Answer

affinity: nodeAntiAffinity

Answer

tolerations

Answer

podSelector

Question 7

Which THREE of the following are core components of a Kubernetes worker node?

Accepted Answer

container runtime. A container runtime is a core component of a Kubernetes worker node. It is responsible for actually running the containers (e.g., containerd, CRI-O) and is required by the kubelet to manage pod lifecycle. Without a container runtime, the kubelet cannot start or stop containers on the node.

Answer

etcd

Answer

kube-apiserver

Question 8

Which TWO of the following statements about Kubernetes namespaces are true?

Accepted Answer

Deleting a namespace will delete all objects in it. Deleting a namespace triggers cascading deletion of all objects within it. Option D is correct because resource quotas can be applied per namespace to limit aggregate resource consumption. Option E is not entirely accurate: namespaces provide logical isolation, but dividing cluster resources among multiple users requires additional mechanisms like RBAC and resource quotas. Without those, namespaces alone do not enforce resource division.

Answer

Services in different namespaces cannot communicate with each other

Answer

Every Kubernetes object must be created in a namespace

Answer

Namespaces provide a way to divide cluster resources between multiple users

Question 9

What is the primary purpose of a Kubernetes Service?

Accepted Answer

To provide a stable endpoint for accessing a set of pods. A Kubernetes Service provides a stable, virtual IP address and DNS name that acts as a consistent endpoint for accessing a set of pods, regardless of pod IP changes due to scaling, restarts, or scheduling. It decouples frontend clients from backend pods by using label selectors to route traffic, ensuring high availability and load balancing across the pod group.

Answer

To manage container image versions

Answer

To store configuration data as key-value pairs

Answer

To schedule pods onto nodes

Question 10

Which command would you use to view the logs of a container named 'web' in a pod named 'frontend' running in the 'production' namespace?

Accepted Answer

kubectl logs frontend -c web -n production. The `kubectl logs` command requires the pod name as the first positional argument, and the `-c` flag specifies the container name when a pod has multiple containers. The `-n` flag sets the namespace. The correct syntax is `kubectl logs -c -n `, which matches option B exactly.

Answer

kubectl logs -c web frontend --namespace production

Answer

kubectl logs frontend -n production container web

Answer

kubectl logs frontend web --namespace production

Question 11

A Deployment named 'nginx' is failing to update. You run 'kubectl rollout status deployment nginx' and see 'Waiting for deployment "nginx" rollout to finish: 0 out of 3 new replicas have been updated...'. The pod template has an image that does not exist. What is the most likely cause?

Accepted Answer

The new image tag is incorrect or does not exist in the registry. The rollout status shows that no new replicas have been created, which is a classic symptom of a container image pull failure. When the image tag specified in the pod template does not exist in the registry, the kubelet cannot pull the image, so the ReplicaSet controller cannot start new pods. This prevents the rollout from progressing past 0 out of 3 new replicas.

Answer

The cluster is out of memory

Answer

The deployment has exceeded the revision history limit

Answer

The deployment is paused

Question 12

You have a multi-container pod with containers 'app' and 'sidecar'. You need to execute a shell command inside the 'sidecar' container. Which kubectl command should you use?

Accepted Answer

kubectl exec -it mypod -c sidecar -- /bin/sh. `kubectl exec` uses the `-c` flag (or `--container`) to specify a target container within a multi-container pod. The syntax `kubectl exec -it mypod -c sidecar -- /bin/sh` opens an interactive shell in the 'sidecar' container of the pod named 'mypod'. Without the `-c` flag, the command defaults to the first container in the pod's spec, which would be 'app'.

Answer

kubectl exec -it mypod -- /bin/sh

Answer

kubectl exec -it sidecar --container mypod -- /bin/sh

Answer

kubectl exec -it mypod --container sidecar -- /bin/sh

Question 13

Which Kubernetes control plane component is responsible for maintaining the desired state of the cluster, such as ensuring the correct number of pods are running?

Accepted Answer

kube-controller-manager. The kube-controller-manager is the control plane component that 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 continuously watches the state of the cluster via the kube-apiserver and makes adjustments to reconcile the current state with the desired state defined in the cluster's configuration.

Answer

kube-apiserver

Answer

kube-scheduler

Answer

etcd

Question 14

You create a Pod with the following YAML. What will happen when you apply it?

Accepted Answer

The Pod will be created with memory limit of 128Mi and CPU limit of 500m. The YAML defines resource limits and requests using standard Kubernetes units: '128Mi' for memory (mebibytes) and '500m' for CPU (millicores). These are valid and will be applied to the container, creating the Pod with the specified limits.

Answer

The Pod will fail to create because memory and CPU are in the wrong unit

Answer

The Pod will be created without resource limits because the syntax is incorrect

Answer

The Pod will be created but requests and limits will be ignored because they are not valid for Pods

Question 15

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