KCNA Practice Exam 54 — 20 Questions

Question 1

Which TWO of the following are features of a service mesh like Istio or Linkerd? (Select 2)

Accepted Answer

Traffic management (routing, load balancing). Service mesh provides observability (metrics, tracing, logs) and traffic management (routing, load balancing). Auto-scaling is not a service mesh feature; it's handled by Kubernetes HPA or Knative. Service discovery is also not a direct feature of service mesh; it's typically provided by Kubernetes DNS.

Answer

Container image building

Answer

Service discovery

Answer

Auto-scaling of services

Question 2

What is the purpose of a Readiness Probe in a Kubernetes pod?

Accepted Answer

To check if the container is ready to start accepting traffic. A Readiness Probe indicates whether a pod is ready to serve traffic; if it fails, the pod is removed from Service endpoints.

Answer

To ensure the pod is scheduled on a specific node

Answer

To restart the container if it becomes unresponsive

Answer

To check if the container is running

Question 3

Which THREE of the following are true about container lifecycle? (Choose 3)

Accepted Answer

A container can be paused and resumed. A container lifecycle includes creation, running, pausing, and stopping. Containers can be started, stopped, and restarted. Containers do not have a 'built' phase; images are built separately. Containers run processes; they are not designed to be hibernated.

Answer

A container can be hibernated to save state to disk

Answer

A container goes through a 'built' phase before running

Question 4

Which two of the following are characteristics of container images built using OCI standards? (Choose two.)

Accepted Answer

They are portable across different container runtimes. OCI images are composed of layers (read-only) and are built from a Dockerfile. They are lightweight and portable across different runtimes. They do not include a guest OS (unlike VMs), and they are not tied to a specific runtime.

Answer

They include a full guest operating system

Answer

They can only be run by Docker

Answer

They require a hypervisor to run

Question 5

An application requires external configuration that varies between environments (dev, staging, prod). Following the 12-factor app methodology, how should this configuration be provided?

Accepted Answer

Use environment variables. The 12-factor app methodology recommends storing configuration in environment variables to keep it separate from code and vary per deploy.

Answer

Store configuration in a config file that is version-controlled

Answer

Use a centralized database for configuration

Answer

Hard-code the configuration in the application code

Question 6

A team is building a serverless application using Knative. They want the application to scale to zero when idle. Which Knative resource type should they use?

Accepted Answer

Knative Serving. Knative Serving manages serverless workloads and supports automatic scaling to zero when no requests are incoming.

Answer

Knative Trigger

Answer

Knative Build

Answer

Knative Eventing

Question 7

Which Prometheus metric type is used to represent a value that can increase or decrease over time, such as memory usage?

Accepted Answer

Gauge. A gauge is a metric that can go up and down, like memory usage or temperature.

Answer

Histogram

Answer

Summary

Answer

Counter

Question 8

An organization uses Flux with Kustomize to manage their Kubernetes applications. They want to automatically update their deployment when a new container image is pushed to the registry. Which Flux component should they use?

Accepted Answer

Image Automation Controller. Flux's Image Automation Controller automates updates based on image policies. It can update manifests in Git when a new image tag is found, triggering a sync.

Answer

Source Controller

Answer

Helm Controller

Answer

Kustomize Controller

Question 9

What is the purpose of the metrics-server in Kubernetes?

Accepted Answer

To provide resource usage metrics for pods and nodes. The metrics-server provides resource metrics (CPU and memory) per pod and node, used by kubectl top and the Horizontal Pod Autoscaler.

Answer

To manage service meshes

Answer

To collect application logs

Answer

To store historical metrics

Question 10

In Prometheus, what is the purpose of the Alertmanager component?

Accepted Answer

To manage, group, and route alerts to notification channels like email or Slack. Alertmanager handles alerts sent by Prometheus server, deduplicates, groups, and routes them to receivers (email, Slack, etc.), and manages silencing and inhibition.

Answer

To scrape metrics from targets

Answer

To provide a graphical dashboard for metrics

Answer

To store historical metrics data long-term

Question 11

What is the primary purpose of a container registry in the CI/CD pipeline?

Accepted Answer

To store and distribute container images. Container registries store container images after they are built, allowing them to be pulled by Kubernetes clusters during deployment. They are the intermediary between CI and CD.

Answer

To run unit tests on container images

Answer

To store application source code

Answer

To scan images for vulnerabilities

Question 12

What type of Prometheus metric is best suited to count the total number of HTTP requests received by a service?

Accepted Answer

Counter. A counter is a cumulative metric that can only increase or be reset to zero, ideal for counting events like requests.

Answer

Histogram

Answer

Gauge

Answer

Summary

Question 13

A team wants to set up alerts when a Kubernetes pod consumes more than 90% of its memory limit for over 5 minutes. They use Prometheus and Alertmanager. Which Prometheus query would trigger an alert for a specific pod named 'web-app' in the 'default' namespace?

Accepted Answer

container_memory_usage_bytes{pod='web-app'} / container_spec_memory_limit_bytes{pod='web-app'} > 0.9. The correct query divides container memory usage by its limit and compares to 0.9.

Answer

container_memory_usage_bytes{pod='web-app'} > 0.9

Answer

avg(container_memory_usage_bytes{pod='web-app'}) > 0.9

Answer

container_memory_limit_bytes{pod='web-app'} > 0.9

Question 14

What is the purpose of values.yaml in a Helm chart?

Accepted Answer

To store default configuration values for the chart. values.yaml provides default configuration values that can be overridden at install/upgrade time.

Answer

To specify the chart metadata

Answer

To define the Kubernetes resources to create

Answer

To define the release name

Question 15

In Kustomize, what is the purpose of an overlay?

Accepted Answer

To apply environment-specific customizations on top of a base. Kustomize overlays allow customizing a base configuration for different environments (e.g., dev, prod) by applying patches without modifying the base.

Answer

To merge multiple Kubernetes manifests into one

Answer

To template variables into YAML files

Answer

To define the base configuration of an application

Question 16

Which log aggregation tool is designed specifically for Kubernetes and is often used as a lightweight alternative to Fluentd?

Accepted Answer

Fluent Bit. Fluent Bit is a lightweight log processor and forwarder, often used in Kubernetes.

Answer

Logstash

Answer

Loki

Answer

Elasticsearch

Question 17

What is context propagation in distributed tracing?

Accepted Answer

Carrying trace context (trace ID, span ID) across services. Context propagation carries trace context across service boundaries to connect spans into a single trace.

Answer

Sampling traces to reduce data volume

Answer

Visualizing traces in a user interface

Answer

Storing trace data in a centralized database

Question 18

What is the primary purpose of structured logging?

Accepted Answer

To format logs in a consistent, machine-readable way for easier processing. Structured logging outputs logs in a consistent, machine-readable format (e.g., JSON) making it easier to parse, filter, and analyze log data.

Answer

To compress log files and reduce storage usage

Answer

To encrypt log data for security purposes

Answer

To send logs directly to the user's terminal

Question 19

Which tool is primarily used for distributed tracing in cloud native environments?

Accepted Answer

Jaeger. Jaeger is a popular open-source distributed tracing system.

Answer

Grafana

Answer

Fluentd

Answer

Prometheus

Question 20

Which THREE of the following are benefits of structured logging? (Select three.)

Accepted Answer

Easier querying and filtering. Structured logging provides machine-parseable output, enables easier querying and analysis, and ensures consistent field naming. Human readability is not a primary benefit; structured logs can be less human-friendly than plain text.

Answer

More human-readable than plain text

Answer

Reduced storage requirements