KCNA Practice Test 6 — 10 Questions

Question 1

Which THREE of the following are valid use cases for distributed tracing in a microservices architecture?

Accepted Answer

Understanding the dependency graph between microservices. Distributed tracing is designed to follow a single request as it propagates across service boundaries, so option B is correct because the spans and parent-child relationships recorded in a trace directly reveal the dependency graph and call topology between microservices. Option C is correct because a trace correlates spans across services with shared trace IDs, letting you locate the exact failing span and thus the root cause of an error in a distributed transaction. Option D is correct because span durations and timestamps expose per-service latency contributions, making it possible to identify which service adds the most latency to an end-user request. Option A is not a tracing use case; CPU and memory usage per instance are collected by metrics/monitoring tools such as Prometheus or CloudWatch, not by distributed tracing. Option E is also not specific to tracing; detailed error messages and stack traces are typically captured by centralized logging or error-tracking systems, even though traces may carry limited error tags.

Answer

Monitoring CPU and memory usage of each service instance

Answer

Capturing detailed error messages and stack traces

Question 2

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 3

Which TWO of the following are functions of the kube-controller-manager?

Accepted Answer

Managing replication and ensuring the desired number of pods are running. Option A is correct because the kube-controller-manager runs the ReplicationController/ReplicaSet controller, which continuously reconciles the actual number of running pods with the desired replica count specified in the resource. Option D is correct because the kube-controller-manager includes the node controller, which monitors node health via heartbeats/leases and responds to node failures by marking nodes NotReady and evicting or rescheduling their pods. Option B is incorrect because cluster state is persisted in etcd, not by the kube-controller-manager. Option C is incorrect because the Kubernetes API is exposed by the kube-apiserver. Option E is incorrect because pod-to-node assignment (scheduling) is performed by the kube-scheduler.

Answer

Storing cluster state

Answer

Exposing the Kubernetes API

Answer

Assigning pods to nodes

Question 4

Which THREE are benefits of using container orchestration platforms like Kubernetes?

Accepted Answer

High availability through automatic container restart and replication. Option A is correct because Kubernetes provides high availability by automatically restarting failed containers and maintaining the desired number of replicas across nodes, ensuring workloads remain available even when individual containers or nodes fail. Option B is correct because Kubernetes supports automatic scaling of container replicas through mechanisms like the Horizontal Pod Autoscaler, which adjusts replica counts based on observed CPU, memory, or custom metrics. Option C is correct because Kubernetes performs self-healing by detecting failed containers, pods, or nodes and replacing or rescheduling them without manual intervention, restoring the declared desired state. Option D is not a benefit of orchestration because Kubernetes manages deployment and runtime concerns, not application source code, so developers still must write and modify code as needed. Option E is incorrect because orchestration platforms do not eliminate monitoring and logging; they integrate with tools like Prometheus, Grafana, and the ELK stack, and observability remains essential for operating containerized workloads.

Answer

Simplified application development by eliminating the need for code changes

Answer

Elimination of the need for monitoring and logging

Question 5

Which command is used to view the logs of a pod named 'web-pod'?

Accepted Answer

kubectl logs web-pod. The correct command to view logs from a pod in Kubernetes is 'kubectl logs web-pod'. This command retrieves the current stdout/stderr output from the primary container in the specified pod, which is the standard method for accessing container logs without entering the pod.

Answer

kubectl describe pod web-pod

Answer

kubectl get logs web-pod

Answer

kubectl exec web-pod -- logs

Question 6

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 7

What is the function of kube-proxy on a worker node?

Accepted Answer

It implements part of the Kubernetes Service concept by managing network rules. kube-proxy runs on each worker node and is responsible for implementing the Kubernetes Service abstraction by managing network rules (e.g., iptables, IPVS, or userspace mode). It watches the API server for Service and EndpointSlice changes and configures local packet filtering or forwarding rules to route traffic to the correct backend pods, enabling load balancing and service discovery.

Answer

It ensures the desired number of pods are running

Answer

It runs the container runtime

Answer

It reports node status to the control plane

Question 8

A user creates a Deployment with 'replicas: 3'. After applying the manifest, only 2 pods are running. What is the most likely cause?

Accepted Answer

There is insufficient node capacity to schedule the third pod. The most likely cause is insufficient node capacity, as the scheduler cannot place the third pod due to resource constraints (CPU, memory, or other limits). The Deployment controller creates a ReplicaSet, which instructs the scheduler to place pods; if nodes lack sufficient allocatable resources, pods remain in Pending state. This is a common scenario when cluster resources are exhausted.

Answer

The Deployment's YAML had a syntax error

Answer

The container image name is misspelled

Answer

The ReplicaSet controller is not running

Question 9

A microservice application is experiencing high latency during traffic spikes. The team identifies that the database connection pool is exhausted. They want to implement a pattern that helps decouple the microservice from direct database connections and smooth out traffic bursts. Which design pattern should they apply?

Accepted Answer

Queue-based Load Leveling pattern. The Queue-based Load Leveling pattern uses a message queue (e.g., RabbitMQ, Amazon SQS) as a buffer between the microservice and the database. When traffic spikes occur, requests are queued and processed at a manageable rate, preventing the database connection pool from being exhausted. This decouples the service from direct database connections and smooths out bursts, directly addressing the latency issue.

Answer

Bulkhead pattern

Answer

Circuit Breaker pattern

Answer

Retry pattern

Question 10

Which of the following is true about Kubernetes Namespaces?

Accepted Answer

Namespaces are used to logically isolate resources like pods and services. Kubernetes Namespaces provide a mechanism to logically isolate resources such as Pods, Services, and Deployments within a single cluster. They enable multi-tenancy by partitioning cluster resources among multiple users or teams, each operating within their own virtual cluster. This logical isolation does not include network segmentation by default, but it allows for resource quota enforcement and access control via RBAC.

Answer

Namespaces can be nested

Answer

Namespaces are required for all resources

Answer

Namespaces provide network isolation by default