KCNA Practice Exam 2 — 20 Questions

Question 1

You need to store a database password securely and expose it to a Pod as an environment variable. Which Kubernetes resource should you use?

Accepted Answer

Secret. A Secret is the correct Kubernetes resource for storing sensitive data like database passwords because it encodes the value in base64 and can be injected into a Pod as an environment variable. Unlike ConfigMaps, Secrets are designed for confidential information and support optional encryption at rest when etcd is configured accordingly.

Answer

Service

Answer

PersistentVolumeClaim

Answer

ConfigMap

Question 2

What is the OCI (Open Container Initiative) responsible for?

Accepted Answer

Defining standards for container images and runtimes. The Open Container Initiative (OCI) is a Linux Foundation project that defines open industry standards for container image formats and container runtimes. Its two main specifications are the OCI Image Spec (which standardizes the container image layout, including layers and manifests) and the OCI Runtime Spec (which defines the lifecycle and configuration for running containers). This ensures interoperability between different container tools and platforms, such as Docker, Podman, and containerd.

Answer

Hosting public container images

Answer

Providing a default container runtime for Kubernetes

Answer

Managing container orchestration

Question 3

A team is designing a cloud-native system that must maintain high availability across multiple cloud regions. The application uses Kubernetes clusters in each region. Which approach best ensures that the system can tolerate a full region failure while minimizing complexity?

Accepted Answer

Use a global load balancer with active-passive regional failover. A global load balancer with active-passive regional failover provides a straightforward way to route traffic to a healthy secondary region when the primary fails, without the complexity of multi-region Kubernetes control planes or synchronous replication. This approach leverages DNS-based or anycast routing to detect region failure and redirect traffic, ensuring high availability while keeping the operational overhead low.

Answer

Deploy a single Kubernetes cluster spanning all regions

Answer

Run active-active in all regions with synchronous data replication

Answer

Implement manual failover procedures documented in runbooks

Question 4

A DevOps team wants to collect and forward logs from all nodes in a Kubernetes cluster to a centralized logging backend. Which component is specifically designed for lightweight log collection and forwarding?

Accepted Answer

Fluent Bit. Fluent Bit is a lightweight log processor and forwarder, ideal for Kubernetes nodes.

Answer

Prometheus

Answer

Jaeger

Answer

Grafana

Question 5

You need to expose a set of pods running a web application to internal cluster traffic on a stable IP address. Which resource should you create?

Accepted Answer

Service of type ClusterIP. A Service of type ClusterIP exposes the set of pods on a stable, internal IP address that is only reachable within the cluster. This is the default Service type and is specifically designed for internal cluster traffic, providing a stable virtual IP (VIP) that load-balances requests to the underlying pods.

Answer

Service of type NodePort

Answer

Ingress

Answer

NetworkPolicy

Question 6

Refer to the exhibit. A pod 'my-pod' shows repeated 'BackOff' events after the container starts. Which is the most likely cause?

Accepted Answer

The application crashes shortly after starting.. The 'BackOff' event in Kubernetes indicates that the container has started but repeatedly crashes, causing the kubelet to increase the restart delay. Option D is correct because an application that crashes shortly after starting will trigger this restart loop, as the container exits with a non-zero exit code, leading to exponential backoff.

Answer

The image 'myapp:v2' does not exist.

Answer

The container exceeds its memory limit.

Answer

The liveness probe is failing.

Question 7

A Kubernetes cluster has two nodes: control-plane and worker. The worker node runs several pods. The control-plane node becomes unreachable. What is the immediate impact on the pods running on the worker node?

Accepted Answer

Pods continue running, but new pods cannot be scheduled. When the control-plane node becomes unreachable, the kube-controller-manager cannot communicate with the kubelet on the worker node, so it stops performing scheduling and reconciliation. However, the kubelet on the worker node continues to run existing pods based on the last known desired state stored locally, and the pods themselves are managed by the container runtime (e.g., containerd) independently of the control-plane. Therefore, pods continue running normally, but no new pods can be scheduled because the scheduler, which runs on the control-plane, is unavailable.

Answer

All pods are immediately terminated

Answer

Pods are rescheduled to the control-plane node

Answer

The worker node is automatically cordoned

Question 8

Which Kubernetes object provides a stable IP address and DNS name for a set of Pods?

Accepted Answer

Service. A Service provides a stable virtual IP address and a DNS name (e.g., my-svc.namespace.svc.cluster.local) that remains constant even as Pods are created or destroyed. This enables reliable network access to a dynamic set of Pods selected via labels, abstracting away Pod IP volatility.

Answer

Ingress

Answer

ConfigMap

Answer

Deployment

Question 9

Which command would you use to view the logs of a container named 'sidecar' inside a pod named 'app'?

Accepted Answer

kubectl logs app -c sidecar. The `kubectl logs` command uses the `-c` flag to specify a container name within a pod. When a pod contains multiple containers, you must explicitly indicate which container's logs to retrieve. The syntax `kubectl logs -c ` is the standard way to view logs from a specific container in a multi-container pod.

Answer

kubectl logs app sidecar

Answer

kubectl logs sidecar app

Answer

kubectl logs sidecar -p app

Question 10

Which THREE of the following are key characteristics of microservices architecture?

Accepted Answer

Independent deployment of services. Microservices architecture mandates that each service can be independently deployed, updated, and scaled without affecting other services. This is achieved through separate deployment pipelines, containerization (e.g., Docker), and orchestration platforms like Kubernetes that manage service lifecycles independently. Independent deployment enables continuous delivery and reduces the blast radius of changes.

Answer

Single monolithic codebase

Answer

Shared database schema across services

Question 11

Which of the following is NOT one of the three pillars of observability in cloud-native environments?

Accepted Answer

Security. The three pillars are logs, metrics, and traces. Security is not one of them, though it is important.

Answer

Metrics

Answer

Traces

Answer

Logs

Question 12

Which Kubernetes control plane component is responsible for maintaining the desired state of the cluster by running reconciliation loops?

Accepted Answer

kube-controller-manager. The kube-controller-manager is the control plane component that runs controller processes, each of which watches the current state of the cluster via the kube-apiserver and makes changes to drive the actual state toward the desired state defined in etcd. This reconciliation loop pattern is fundamental to Kubernetes' self-healing behavior, ensuring that resources like deployments, replica sets, and nodes match their specifications.

Answer

kube-scheduler

Answer

etcd

Answer

kube-apiserver

Question 13

You need to ensure that a set of pods in a Deployment can be reached by other pods using a stable IP address and DNS name. Which Kubernetes object should you use?

Accepted Answer

Service. A Service provides a stable IP address and DNS name for a set of pods, abstracting the underlying pod IPs that can change due to scaling or failures. By default, a Service uses a cluster-internal virtual IP and DNS record (e.g., ..svc.cluster.local) that other pods can resolve, ensuring reliable connectivity without needing to track individual pod IPs.

Answer

NetworkPolicy

Answer

Ingress

Answer

ConfigMap

Question 14

An application running in a Kubernetes cluster needs to securely access a third-party API. The API key must be stored in the cluster and mounted into the Pod as an environment variable. Which is the best practice?

Accepted Answer

Create a Secret with the API key and use envFrom or valueFrom in the Pod spec.. Kubernetes Secrets are specifically designed to store sensitive data like API keys, and using `envFrom` or `valueFrom` in the Pod spec injects the Secret value as an environment variable without exposing it in the Pod definition. This approach follows the principle of least privilege and avoids hardcoding secrets in images or plaintext ConfigMaps.

Answer

Store the API key in a ConfigMap and reference it in the Pod spec.

Answer

Embed the API key directly in the container image.

Answer

Store the API key in a Pod annotation and read it with kubectl.

Question 15

Which command is used to create a Deployment that runs an nginx container with 3 replicas?

Accepted Answer

kubectl create deployment nginx --image=nginx --replicas=3. `kubectl create deployment` is the standard Kubernetes command to create a Deployment resource, and the `--replicas=3` flag directly sets the desired replica count to 3. This command creates a Deployment that manages a ReplicaSet to ensure three nginx pods are running and maintained.

Answer

kubectl create pod nginx --image=nginx --replicas=3

Answer

kubectl run nginx --image=nginx --replicas=3

Answer

kubectl scale deployment nginx --replicas=3

Question 16

According to DORA metrics, which metric measures the percentage of deployments that fail in production?

Accepted Answer

Change Failure Rate. Change Failure Rate (CFR) is the DORA metric that directly measures the percentage of deployments that result in a failure in production, such as a service outage or a bug requiring a hotfix. It is calculated as (number of failed deployments / total deployments) * 100. This metric reflects the quality and stability of the software delivery process, complementing speed metrics like Deployment Frequency and Lead Time for Changes.

Answer

Mean Time to Restore (MTTR)

Answer

Deployment Frequency

Answer

Lead Time for Changes

Question 17

A pod is stuck in the Pending state. Running 'kubectl describe pod <pod-name>' shows the event: '0/3 nodes are available: 1 node had taint {node.kubernetes.io/disk-pressure: }, 2 nodes had taint {node.kubernetes.io/memory-pressure: }'. What is the most likely cause?

Accepted Answer

All nodes have taints that the pod does not have tolerations for. The pod is stuck in Pending because the scheduler cannot find a node that satisfies its scheduling constraints. The events show that all three nodes have taints (disk-pressure and memory-pressure), and the pod does not have corresponding tolerations to allow it to be scheduled on those nodes. Without tolerations, the pod is not permitted to run on any of the available nodes, leaving it in the Pending state.

Answer

The container image is not found in the registry

Answer

The pod has a resource request that exceeds available capacity on all nodes

Answer

The pod's liveness probe is failing

Question 18

A Service of type ClusterIP is created to expose a set of pods. How does the Service achieve load balancing to the pods?

Accepted Answer

The kube-proxy component on each node sets up network rules to forward traffic to the pods. Kube-proxy on each node implements load balancing for ClusterIP Services by creating iptables or IPVS rules that distribute traffic from the Service's virtual IP to the backend pods. These rules use a random or round-robin selection (depending on the mode) to forward packets to healthy pods, ensuring no single pod is overwhelmed.

Answer

The API server routes traffic directly to the pods

Answer

The kubelet configures the container runtime to route traffic

Answer

Using a cloud load balancer

Question 19

Which two of the following are Kubernetes controllers that run inside the kube-controller-manager? (Select TWO)

Accepted Answer

Replication controller. The Replication controller (B) is correct because it is a built-in controller that runs within the kube-controller-manager process, continuously reconciling the desired number of pod replicas with the actual state by creating or deleting pods. The Node controller (D) is also correct because it is another controller embedded in the kube-controller-manager, responsible for monitoring node health, applying taints like node.kubernetes.io/not-ready, and evicting pods from unreachable nodes. The kubelet (A) is not part of the kube-controller-manager; it is a node-level agent that runs on each worker node and manages pod lifecycle via the container runtime. etcd (C) is the distributed key-value store that persists cluster state, not a controller, and it runs as a separate process. The kube-scheduler (E) is a separate control-plane component that assigns pods to nodes and runs independently of the kube-controller-manager.

Answer

kubelet

Answer

etcd

Answer

kube-scheduler

Question 20

Which TWO are characteristics of the microservices architecture that are supported by container orchestration?

Accepted Answer

Independent deployment of each service. Option B is correct because container orchestration platforms such as Kubernetes let each microservice be built, versioned, and rolled out on its own schedule, so a change to one service does not force redeployment of the others. Option C is correct because microservices architecture decomposes an application into small, independently runnable services, and orchestration supports this by scheduling, scaling, and networking each service as a separate workload. Options A, D, and E are not characteristics of microservices supported by orchestration: tight coupling, a monolithic codebase with centralized deployment, and a single shared database all describe monolithic or tightly integrated designs that contradict the independence and loose coupling that orchestration enables.

Answer

Tight coupling between services to ensure performance

Answer

Monolithic codebase with centralized deployment

Answer

Use of a single, shared database for all services