KCNA Practice Exam 52 — 20 Questions

Question 1

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 2

Which command correctly creates a Deployment named 'web-app' with the image 'nginx:1.21' and 3 replicas?

Accepted Answer

kubectl create deployment web-app --image=nginx:1.21 --replicas=3. `kubectl create deployment` is the imperative command specifically designed to create a Deployment resource in Kubernetes. The `--image` flag specifies the container image, and `--replicas=3` sets the desired number of pod replicas, which matches the requirement exactly.

Answer

kubectl apply deployment web-app --image=nginx:1.21 --replicas=3

Answer

kubectl run web-app --image=nginx:1.21 --replicas=3

Answer

kubectl create deployement web-app --image=nginx:1.21 --replicas=3

Question 3

A developer creates a Deployment with 3 replicas. The developer runs 'kubectl get pods' immediately after creation and sees that only 1 pod is in Running state, and the other 2 are Pending. What is the most likely reason for this?

Accepted Answer

The cluster does not have enough resources (CPU/memory) to schedule the additional pods. When a Pod remains in Pending state, it indicates that the scheduler cannot find a suitable node to place it. The most common cause is insufficient cluster resources (CPU or memory) to accommodate the additional Pods, as the scheduler checks node allocatable resources against Pod resource requests. With 2 out of 3 Pods pending, the cluster likely has enough resources for only one replica, leaving the others unscheduled.

Answer

The Deployment's YAML has a syntax error

Answer

The container image is not available on the worker nodes

Answer

The kubelet on the node is not running

Question 4

A container image built using a Dockerfile with multiple layers is stored in a registry. When a node pulls this image, which statement about layers is true?

Accepted Answer

Layers that are already cached on the node are reused and only new layers are downloaded. Container images are composed of read-only layers, each representing a set of filesystem changes. When a node pulls an image, the container runtime (e.g., containerd or CRI-O) checks its local layer cache against the manifest's layer digests (SHA256 hashes). Layers already present locally are reused, and only missing layers are downloaded from the registry, which optimizes bandwidth and storage.

Answer

Layers are merged into a single layer before download

Answer

All layers must be downloaded each time the image is pulled

Answer

Only the topmost layer is downloaded; lower layers are streamed from the registry

Question 5

You have a Deployment with image: myapp:v1. You update the image to myapp:v2 using 'kubectl set image deployment/myapp myapp=myapp:v2'. The rollout status shows 'Waiting for rollout to finish: 0 out of 3 new replicas have been updated...'. What is the most likely cause of this behavior?

Accepted Answer

The new image myapp:v2 does not exist or cannot be pulled from the registry. The rollout is stuck waiting for new replicas to become ready, which typically happens when the container image cannot be pulled. The message '0 out of 3 new replicas have been updated' indicates that the ReplicaSet is attempting to create Pods with the new image, but the Pods are failing to start. The most common cause is that the image tag 'myapp:v2' does not exist in the registry or cannot be accessed due to authentication or network issues, preventing the kubelet from pulling it.

Answer

The command syntax is incorrect; you should use 'kubectl set image deployment/myapp myapp:v2'

Answer

The new Pods are crashing due to a missing command

Answer

The Deployment's update strategy is set to 'Recreate'

Question 6

A pod has resource requests set to 'cpu: 500m' and 'memory: 256Mi'. The node has 2 CPU cores and 4Gi memory. How many pods with the same resource requests can be scheduled on that node, assuming no other pods?

Accepted Answer

4. Each pod requests 0.5 CPU cores (500m) and 256 MiB of memory. The node has 2 CPU cores, so the CPU limit allows 2 / 0.5 = 4 pods. The node has 4 GiB of memory (4096 MiB), so the memory limit allows 4096 / 256 = 16 pods. The tighter constraint is CPU, which permits exactly 4 pods. Option B is correct.

Answer

2

Answer

8

Answer

16

Question 7

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

Accepted Answer

etcd. etcd (A) is correct because it is the control plane's distributed key-value store that persists all cluster state and configuration data, and kube-apiserver (C) is correct because it is the control plane component that exposes the Kubernetes API and serves as the front end through which all other components communicate. The other options are node-level components, not control plane components: kube-proxy (B) maintains network rules for Service traffic on each node, kubelet (D) runs on each node to manage Pods and containers, and the container runtime (E) is the software on each node that actually runs containers.

Answer

kube-proxy

Answer

kubelet

Answer

container runtime

Question 8

Which of the following is a key principle of the 12-factor app methodology related to managing configuration?

Accepted Answer

Use environment variables for configuration. The 12-factor app methodology's third factor, 'Config,' states that configuration should be stored in the environment (environment variables), not in the code. This separates config from code, allowing the same build to be deployed across environments (dev, staging, prod) without modification. Environment variables are language-agnostic and easily changed per deployment.

Answer

Store configuration in the application code

Answer

Embed configuration in the build process

Answer

Use a configuration file in the application directory

Question 9

In a service mesh architecture, which component is responsible for intercepting and managing traffic between microservices?

Accepted Answer

Sidecar proxy. In a service mesh, the sidecar proxy is deployed alongside each microservice instance and transparently intercepts all inbound and outbound network traffic. It enforces policies, collects telemetry, and manages routing without requiring changes to the application code. The control plane configures these proxies but does not handle the actual data path.

Answer

Control plane

Answer

API gateway

Answer

Service registry

Question 10

A DevOps team wants to collect logs from all Kubernetes nodes and forward them to a central log storage system. Which tool is specifically designed for lightweight log aggregation and forwarding on Kubernetes nodes?

Accepted Answer

Fluent Bit. Fluent Bit is a lightweight, high-performance log processor and forwarder designed specifically for resource-constrained environments like Kubernetes nodes. It runs as a DaemonSet, tails container log files from /var/log/containers, and forwards them to a central backend such as Elasticsearch, Loki, or Splunk. Its low CPU and memory footprint make it the standard choice for node-level log aggregation.

Answer

Elasticsearch

Answer

Prometheus

Answer

Grafana

Question 11

A team wants to deploy a workload that must run on every node in a Kubernetes cluster, including new nodes added later. Which resource type should they use?

Accepted Answer

DaemonSet. A DaemonSet ensures that a copy of a specific pod runs on every node in the cluster, including nodes added later. This is ideal for cluster-wide services like log collectors, monitoring agents, or network plugins that must run on all nodes.

Answer

Deployment

Answer

Job

Answer

StatefulSet

Question 12

Which THREE of the following are components of the OpenTelemetry project? (Select three)

Accepted Answer

OpenTelemetry API. The OpenTelemetry API (option B) is a core component that defines the interfaces and instrumentation primitives (Tracer, Meter, Logger) that application code uses to generate telemetry, independent of any implementation. The OpenTelemetry SDK (option C) is the concrete implementation of that API, providing the processing pipeline (span processors, samplers, exporters, resource detection) that turns API calls into exportable telemetry. The OpenTelemetry Collector (option D) is a standalone, vendor-agnostic service that receives, processes, and exports telemetry data via receivers, processors, and exporters, and is a distinct official component of the project. Option A is incorrect because there is no product called the 'OpenTelemetry Agent'; the project ships an SDK and the Collector, not an agent by that name. Option E is incorrect because an exporter is a subcomponent within the SDK or Collector pipeline, not a top-level OpenTelemetry project component.

Answer

OpenTelemetry Agent

Answer

OpenTelemetry Exporter

Question 13

A startup wants to minimize downtime during application updates in Kubernetes. Which deployment strategy should they use?

Accepted Answer

RollingUpdate. The RollingUpdate strategy is the default in Kubernetes and minimizes downtime by gradually replacing old Pods with new ones while the application remains available. It uses a configurable `maxSurge` and `maxUnavailable` parameters to control the rate of change, ensuring that a specified number of Pods are always serving traffic. This makes it ideal for startups seeking zero-downtime updates without the complexity of additional tooling or infrastructure.

Answer

Canary

Answer

Blue/Green

Answer

Recreate

Question 14

Which three of the following are benefits of container orchestration? (Choose three.)

Accepted Answer

High availability through replication. Container orchestration platforms such as Kubernetes and Docker Swarm provide high availability through replication (A) by running multiple identical instances of a service across nodes, so the failure of one replica or node does not take the service down. They also enable scaling services up or down (B) declaratively, adjusting the number of replicas to match demand via controllers like Deployments or ReplicaSets. Self-healing by restarting failed containers (D) is a core orchestration capability: the orchestrator monitors container and node health and automatically reschedules or restarts containers that crash or become unresponsive. Option C is incorrect because orchestration automates scheduling and placement of containers rather than requiring manual deployment to specific hosts, which is the opposite of its benefit. Option E is incorrect because bare metal performance is a characteristic of running directly on hardware, not a benefit provided by orchestration, which typically adds an abstraction layer.

Answer

Manual deployment of containers to specific hosts

Answer

Bare metal performance

Question 15

Which THREE are responsibilities of the OpenTelemetry project? (Select three.)

Accepted Answer

Provide instrumentation libraries. Option C is correct because OpenTelemetry provides language-specific instrumentation libraries (for Java, Python, Go, JavaScript, .NET, etc.) and APIs/SDKs that generate traces, metrics, and logs. Option D is correct because OpenTelemetry defines vendor-neutral specifications and semantic conventions for telemetry data, including the OTLP wire protocol, so signals are portable across tools. Option E is correct because the OpenTelemetry Collector is a vendor-agnostic component that receives, processes, and exports telemetry via receivers, processors, and exporters. Option A is not a responsibility of OpenTelemetry itself; visualization is handled by backends such as Jaeger, Prometheus, Grafana, or commercial APM UIs. Option B is also not a responsibility of OpenTelemetry; long-term storage is provided by backend observability platforms, not by the OpenTelemetry project.

Answer

Visualize telemetry data

Answer

Store long-term telemetry data

Question 16

Which THREE of the following are benefits of using an event-driven architecture? (Choose three.)

Accepted Answer

Better resilience through decoupled components. Option B is correct because event-driven architecture decouples producers from consumers, so if one component fails or is slow, others can continue operating and events can be buffered or retried, improving overall resilience. Option C is correct because asynchronous processing lets events be queued and consumed independently, allowing components to scale out horizontally based on event volume rather than being blocked by synchronous calls. Option E is correct because services communicate through events via a broker or event bus rather than direct point-to-point calls, which reduces dependencies and enforces loose coupling between services. Option A is not correct because event-driven systems typically make debugging and tracing harder, since flows span multiple asynchronous hops and require correlation IDs and distributed tracing. Option D is not correct because event-driven architectures still require robust monitoring, observability, and alerting to track event flows, broker health, and consumer lag.

Answer

Simpler debugging and tracing

Answer

Reduced need for monitoring

Question 17

A developer creates a Deployment with 3 replicas. After updating the pod template, they run 'kubectl rollout status deployment/my-deployment' and see that the rollout is stuck. Which command should they use to investigate the rollout history?

Accepted Answer

kubectl rollout history deployment/my-deployment. 'kubectl rollout history' is the dedicated command to view the revision history of a Deployment, including the changes made to the pod template in each revision. When a rollout is stuck, this command helps identify which revision caused the issue and allows you to roll back to a previous stable revision. The other commands provide general debugging information but do not specifically show the rollout history.

Answer

kubectl get events

Answer

kubectl describe deployment my-deployment

Answer

kubectl logs deployment/my-deployment

Question 18

Which THREE of the following are benefits of using a service mesh in a cloud native architecture?

Accepted Answer

Traffic management capabilities like canary deployments. Option B is correct because a service mesh provides layer-7 traffic management (e.g., weighted routing, header-based routing) that enables canary deployments and blue/green releases without changing application code. Option D is correct because service meshes like Istio and Linkerd automatically provision and rotate mutual TLS (mTLS) certificates between sidecar proxies, giving strong service-to-service authentication and encryption. Option E is correct because sidecar proxies emit uniform telemetry—request metrics, distributed traces, and access logs—across all services, improving observability without per-service instrumentation. Option A is not a service mesh benefit: application state management is handled by databases, caches, or stateful orchestration, not by the mesh's data plane. Option C is also incorrect because the mesh adds sidecar proxies and control-plane components, which tend to increase rather than reduce container image sizes.

Answer

Management of application state across services

Answer

Reduction of container image sizes

Question 19

Which TWO of the following are valid Prometheus metric types?

Accepted Answer

Counter. Option B (Counter) is correct because Prometheus defines the counter metric type as a cumulative value that only increases or resets to zero on restart, typically used for counts of events or errors. Option E (Gauge) is correct because Prometheus defines the gauge metric type as a value that can arbitrarily go up and down, used for measurements like temperature, memory usage, or current queue size. The other options are not Prometheus metric types: Quantile (A) is a concept used in summary/histogram quantile calculations rather than a metric type itself, while Timer (C) and Meter (D) are metric types from other monitoring libraries such as Dropwizard Metrics or Micrometer, not native Prometheus types.

Answer

Quantile

Answer

Timer

Answer

Meter