KCNA Practice Exam 54 — 20 Questions

Question 1

Which of the following is used to logically isolate resources within a Kubernetes cluster?

Accepted Answer

Namespaces. Namespaces provide logical isolation for resources. Option C is correct.

Answer

Annotations

Answer

Selectors

Answer

Labels

Question 2

Which TWO of the following statements about Kubernetes Deployments are correct? (Select 2)

Accepted Answer

Deployments support rolling updates and rollbacks. Option A is correct because a Deployment's pod template can be updated declaratively, and the Deployment controller performs a rolling update by creating a new ReplicaSet and gradually scaling it up while scaling the old one down, with `kubectl rollout undo` providing rollback to a previous revision. Option D is correct because a Deployment does not manage Pods directly; it creates and manages ReplicaSets, which in turn maintain the desired number of Pod replicas, and each template change produces a new ReplicaSet revision. Option B is wrong because running one Pod copy per node is the job of a DaemonSet, not a Deployment. Option C is wrong because run-to-completion batch workloads are handled by Jobs (or CronJobs), whereas Deployments are intended for long-running stateless services. Option E is wrong because stable network identities and per-Pod DNS names are provided by a headless Service (typically with a StatefulSet), not by a Deployment.

Answer

Deployments ensure that a copy of a Pod runs on each node in the cluster

Answer

Deployments are used for batch processing jobs that run to completion

Answer

Deployments provide stable network identities for Pods

Question 3

Which TWO of the following are principles of the 12-factor app? (Choose two.)

Accepted Answer

Config. Config is a core principle of the 12-factor app methodology, which mandates strict separation of configuration from code. Configuration (such as database URLs, credentials, or hostnames) must be stored in environment variables, not hardcoded in the application source. This allows the same codebase to be deployed across different environments (development, staging, production) without modification, adhering to the principle of config-driven behavior.

Answer

Monolithic deployment

Answer

Stateful sessions

Answer

Manual provisioning

Question 4

In event-driven architecture, what is the role of an event broker?

Accepted Answer

It stores events and enables asynchronous communication between producers and consumers. An event broker acts as a central intermediary that receives events from producers, stores them durably (often in a log or queue), and delivers them to consumers asynchronously. This decouples producers and consumers, allowing them to operate independently without blocking or direct knowledge of each other. Technologies like Apache Kafka, RabbitMQ, or AWS Kinesis exemplify this role by persisting events and enabling replay, fan-out, and load-leveling.

Answer

It executes business logic in response to events

Answer

It provides a user interface to view events

Answer

It converts events into HTTP requests

Question 5

Which TWO of the following are benefits of using a service mesh? (Choose two.)

Accepted Answer

Improved observability of service-to-service communication. Service mesh provides improved observability and enables traffic management features like canary deployments.

Answer

Direct management of virtual machines

Answer

Automated container image building

Answer

Replacing the need for a container runtime

Question 6

A team deploys a microservice that requires sticky sessions. The service runs on Kubernetes with multiple replicas. Which Kubernetes resource should be used to ensure requests from a client are consistently routed to the same pod?

Accepted Answer

Service with sessionAffinity: ClientIP. Setting `sessionAffinity: ClientIP` on a Kubernetes Service ensures that all requests from the same client IP are routed to the same Pod. This is the standard Kubernetes mechanism for implementing sticky sessions without requiring changes to the application or ingress layer.

Answer

Headless Service

Answer

Ingress with default settings

Answer

Deployment with hostNetwork: true

Question 7

You have a Deployment defined with replicas: 3. You run 'kubectl scale deployment my-deployment --replicas=5'. What happens?

Accepted Answer

The Deployment is updated to have 5 replicas, and the ReplicaSet creates 2 additional pods.. `kubectl scale` directly updates the `.spec.replicas` field of the Deployment, which in turn instructs the existing ReplicaSet to adjust its pod count. The ReplicaSet controller then creates 2 additional Pods to reach the desired 5 replicas, without recreating existing Pods or triggering a rollout.

Answer

The Deployment is updated to have 5 replicas, but existing pods are recreated to match.

Answer

The command fails because you cannot scale a Deployment directly.

Answer

The Deployment rolls out a new version with 5 replicas.

Question 8

Which of the following is an example of immutable infrastructure?

Accepted Answer

Rebuilding a server from a pre-baked image and replacing the old one. Immutable infrastructure means that once a server or container is deployed, it is never modified in place. Instead, any change requires building a new image and redeploying. Option D describes exactly this: rebuilding from a pre-baked image and replacing the old server, which is the core pattern of immutability in container orchestration (e.g., Kubernetes rolling updates or Recreate deployments).

Answer

SSH into a server to apply patches

Answer

Manually installing packages on a running container

Answer

Using configuration management tools to update software on running servers

Question 9

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 10

Which Kubernetes controller ensures that a specified number of pod replicas are running at all times?

Accepted Answer

ReplicaSet. A ReplicaSet is the Kubernetes controller that ensures a specified number of pod replicas are running at all times. It uses a label selector to match pods and maintains the desired replica count by creating or deleting pods as needed. ReplicaSet is the successor to ReplicationController and is primarily used by Deployments to manage pod scaling and self-healing.

Answer

Job

Answer

ReplicationController

Answer

DaemonSet

Question 11

In distributed tracing, what is a 'span'?

Accepted Answer

A single logical operation within a trace. A span represents a single logical operation within a trace, such as an HTTP request, a database query, or a function call. It has a start time, duration, and metadata, and spans are nested to form the trace tree. This is the fundamental unit of work in distributed tracing.

Answer

A metric measuring request latency

Answer

A collection of related traces

Answer

A log entry with trace context

Question 12

An organization wants to adopt a cloud-native approach for its new application. Which characteristic is most important for the application to be considered cloud-native?

Accepted Answer

It is designed to be resilient, scalable, and manageable in a dynamic environment.. Cloud-native applications are fundamentally defined by their ability to operate in dynamic, distributed environments. They leverage principles like microservices, containerization, and orchestration (e.g., Kubernetes) to achieve resilience, scalability, and manageability. This characteristic is the core tenet of cloud-native architecture as defined by the CNCF, enabling the app to handle failures gracefully and scale on demand.

Answer

It stores all state in local files on the container filesystem.

Answer

It runs as a single monolithic process for simplicity.

Answer

It is deployed exclusively on on-premises infrastructure.

Question 13

A company wants to adopt immutable infrastructure for its containerized applications. Which practice BEST exemplifies immutability?

Accepted Answer

When a container fails, the orchestrator terminates it and launches a new container from the same image. Immutable infrastructure means that once a container is deployed from a specific image, it is never modified in place. When a container fails, the orchestrator (e.g., Kubernetes) terminates it and launches a new container from the same image, ensuring consistency and reproducibility. This approach eliminates configuration drift and aligns with the principle that all changes should be made by rebuilding the image, not by altering running instances.

Answer

Developers use kubectl exec to change environment variables in a running pod

Answer

A configuration management tool runs periodically to ensure containers are up-to-date

Answer

An operator logs into a running container and applies a security patch with apt-get update

Question 14

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 15

Which component is the primary entry point for all administrative tasks and API requests in a Kubernetes control plane?

Accepted Answer

kube-apiserver. The kube-apiserver is the front-end of the Kubernetes control plane and the only component that directly interacts with etcd. All administrative tasks (via kubectl), API requests from pods, and internal control plane components (scheduler, controller-manager) must pass through the kube-apiserver, which validates and processes them before persisting state or triggering actions.

Answer

etcd

Answer

kube-scheduler

Answer

kube-controller-manager

Question 16

You create a Deployment with 'replicas: 3' and update the pod template to use a new image. After the rollout, you notice that the new ReplicaSet has 3 pods but they are all failing with 'CrashLoopBackOff'. You want to rollback to the previous working revision. Which command should you run?

Accepted Answer

kubectl rollout undo deployment/my-deployment. `kubectl rollout undo deployment/my-deployment` reverts the Deployment to the previous revision, which is the standard Kubernetes method to roll back a failed rollout. This command restores the pod template from the last working ReplicaSet, effectively undoing the change that caused the CrashLoopBackOff.

Answer

kubectl set image deployment/my-deployment nginx=nginx:1.21

Answer

kubectl delete deployment/my-deployment --cascade=false

Answer

kubectl rollout pause deployment/my-deployment

Question 17

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 18

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

Accepted Answer

kube-apiserver. The kube-apiserver (option D) is the central control plane component that exposes the Kubernetes API, validating and processing all REST requests and serving as the front end for the cluster's shared state in etcd. The kube-scheduler (option E) is also a control plane component, responsible for watching for newly created Pods with no assigned node and selecting an appropriate node based on resource requirements, affinity rules, and other constraints. By contrast, kube-proxy (A) runs on each node and maintains network rules for Service traffic, the kubelet (B) is a node agent that ensures containers described in PodSpecs are running, and the container runtime (C) is the software on each node that actually runs containers — all three are node components, not control plane components.

Answer

kube-proxy

Answer

kubelet

Answer

container runtime

Question 19

A DevOps team wants to implement GitOps for their Kubernetes cluster. Which tool is specifically designed for Kubernetes GitOps and can automatically sync the cluster state with a Git repository?

Accepted Answer

ArgoCD. ArgoCD is a declarative, GitOps continuous delivery tool designed specifically for Kubernetes. It continuously monitors a Git repository and automatically syncs the cluster state to match the desired state defined in Git, making it the correct choice for Kubernetes GitOps.

Answer

Jenkins

Answer

Kustomize

Answer

Helm

Question 20

Which of the following is considered one of the three pillars of observability?

Accepted Answer

Metrics. The three pillars of observability in cloud native environments are logs, metrics, and traces.

Answer

Events

Answer

Alerts

Answer

Profiles