KCNA Practice Test 18 — 15 Questions

Question 1

An administrator runs 'kubectl get pods' and sees that a pod is in 'Pending' state. 'kubectl describe pod' shows the event: '0/4 nodes are available: 1 node had taints that the pod didn't tolerate, 3 nodes had insufficient memory'. What is the most likely issue?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

The pod's resource requests exceed available memory on three nodes.. The scheduler event explicitly states '3 nodes had insufficient memory', which directly indicates that the pod's resource requests (specifically memory) exceed the available allocatable memory on those three nodes. The fourth node is unavailable due to taints, leaving zero schedulable nodes, hence the 'Pending' state.

Answer

The node with the taint has a toleration mismatch.

Answer

The pod's image pull is failing.

Answer

The pod was evicted due to resource pressure.

Question 2

What is the primary benefit of using containers over virtual machines?

Accepted Answer

Containers are lightweight and share the host OS kernel. Containers are lightweight because they share the host OS kernel, avoiding the overhead of a separate guest OS per instance. Unlike VMs, which require a hypervisor and a full OS for each virtual machine, containers run as isolated processes on the same kernel, enabling faster startup times and higher density. This shared-kernel model is the primary benefit, as it reduces resource consumption and improves efficiency in orchestrated environments like Kubernetes.

Answer

Containers provide stronger isolation between applications

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Containers include a full operating system per instance

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Containers require a hypervisor to run

Question 3

Which THREE of the following are required for a Kubernetes pod to be considered healthy and ready to serve traffic?

Accepted Answer

The startup probe has succeeded.. A startup probe must succeed before the kubelet considers the container started. Until the startup probe succeeds, the readiness and liveness probes are not active, so the pod cannot be marked healthy or ready. This is defined in the Kubernetes API for startup probes, which delay the start of other probes until the application has initialized.

Answer

The pod has at least one endpoint in its Service's endpoints list.

Answer

The liveness probe has succeeded.

Question 4

A microservices application has multiple services that need to discover each other by name. Which Kubernetes object provides built-in service discovery via DNS?

Accepted Answer

Service. A Kubernetes Service object provides built-in service discovery via DNS. When a Service is created, the cluster's DNS (typically CoreDNS) automatically assigns it a DNS name in the format `..svc.cluster.local`, allowing other microservices to resolve the Service by name without hardcoding IP addresses or using external service registries.

Answer

Ingress

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Namespace

Answer

ConfigMap

Question 5

Which command would you use to view the logs of a specific container in a multi-container pod, using the short flag?

Accepted Answer

kubectl logs mypod -c mycontainer. The command `kubectl logs mypod -c mycontainer` uses the short flag `-c` to specify the container name in a multi-container pod. The long form `--container` also works, but the exam may specifically expect the short flag syntax. Option A uses `-p` which retrieves logs from a previous instance. Option D provides the container name as a positional argument, which is incorrect.

Answer

kubectl logs mycontainer -p mypod

Answer

kubectl logs mypod --container mycontainer

Answer

kubectl logs mypod mycontainer

Question 6

In a service mesh architecture, which component is responsible for intercepting and managing traffic to and from a pod?

Accepted Answer

Sidecar proxy. The sidecar proxy (e.g., Envoy) runs alongside each service instance and intercepts all network traffic, enabling features like traffic management and observability.

Answer

Ingress controller

Answer

API gateway

Answer

Control plane

Question 7

Which TWO statements correctly describe the purpose of etcd in a Kubernetes cluster?

Accepted Answer

It stores the cluster state, including all Kubernetes objects.. Etcd is the primary data store for all Kubernetes cluster state, including the configuration and status of every Kubernetes object (Pods, Services, Deployments, etc.). It stores this information as key-value pairs, and the Kubernetes API server is the only component that reads from and writes to etcd directly. Without etcd, the cluster would have no persistent record of its desired or current state.

Answer

It manages network rules for Pod-to-Pod communication.

Answer

It schedules Pods onto nodes based on resource availability.

Answer

It exposes the Kubernetes API for external access.

Question 8

Which TWO statements about the Container Runtime Interface (CRI) are correct? (Select 2)

Accepted Answer

CRI allows Kubernetes to use different container runtimes. The Container Runtime Interface (CRI) is a plugin interface that enables kubelet to use a variety of container runtimes without needing to recompile Kubernetes. It defines the API between kubelet and the container runtime, allowing runtimes like containerd and CRI-O to be swapped in seamlessly. This abstraction decouples Kubernetes from any single runtime, enabling flexibility and vendor neutrality.

Answer

Docker is the primary CRI implementation

Answer

CRI is responsible for pulling container images

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CRI is an OCI specification

Question 9

Which resource in Kubernetes is used to expose a set of pods as a network service?

Accepted Answer

Service. A Service in Kubernetes provides a stable network endpoint (IP address and DNS name) to expose a set of pods, which are ephemeral and can be replaced. Services use selectors to identify target pods and load-balance traffic across them, enabling reliable communication within or outside the cluster.

Answer

Pod

Answer

Deployment

Answer

Ingress

Question 10

Which TWO are benefits of using a container orchestration platform like Kubernetes? (Select TWO.)

Accepted Answer

Automatic service discovery and load balancing. Kubernetes includes built-in service discovery and load balancing. Services in Kubernetes get a stable virtual IP and DNS name, and kube-proxy implements load balancing across pods using iptables or IPVS rules, distributing traffic without manual configuration.

Answer

Increases application complexity

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Requires a dedicated hypervisor for each container

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Manual scaling of applications

Question 11

Which TWO of the following are benefits of using a multi-cloud strategy? (Select TWO.)

Accepted Answer

Improved resilience and disaster recovery. A multi-cloud strategy distributes workloads across multiple cloud providers, so if one provider experiences an outage, applications can failover to another provider, improving overall resilience and disaster recovery. Option C is correct because using multiple cloud providers prevents dependency on a single vendor's proprietary services, avoiding vendor lock-in and giving you leverage for pricing and feature negotiations.

Answer

Reduced network latency

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Simplified compliance

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Increased vendor lock-in

Question 12

Which THREE of the following are valid ways to expose a set of pods as a network service in Kubernetes?

Accepted Answer

ClusterIP. A ClusterIP service exposes the set of pods on a cluster-internal IP address, making it reachable only from within the cluster. This is the default service type in Kubernetes and is valid for internal communication between workloads. It does not provide external access, but it is a core method for exposing pods as a network service.

Answer

Ingress

Answer

ExternalName

Question 13

What is the primary purpose of structured logging?

Accepted Answer

To enable automated analysis and querying of logs. Structured logging formats log data in a consistent, machine-parseable format (e.g., JSON) with key-value pairs. This enables automated tools like Elasticsearch, Loki, or Splunk to efficiently index, search, filter, and aggregate logs, which is essential for observability at scale. The primary purpose is to facilitate automated analysis and querying, not to replace other telemetry signals or to focus on human readability alone.

Answer

To replace metrics and traces

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To reduce the size of log files

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To make logs human-readable only

Question 14

You are implementing an API gateway pattern for a set of microservices. Which of the following is a typical responsibility of an API gateway?

Accepted Answer

Enforcing authentication and rate limiting. An API gateway handles cross-cutting concerns like authentication, rate limiting, routing, and aggregation. Direct database access (B) is an antipattern, managing container lifecycle (A) is Kubernetes' job, and storing application state (C) is not a gateway function.

Answer

Managing container lifecycle and scaling

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Directly accessing databases to serve requests

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Storing application state and session data

Question 15

You run 'kubectl get pods' and see that a pod named 'web-frontend' is in 'Pending' state for more than 5 minutes. What is the most likely cause?

Accepted Answer

There are insufficient resources on any node to schedule the pod. A pod stuck in 'Pending' state for an extended period typically indicates that the scheduler cannot find a suitable node to run the pod. The most common reason is insufficient resources (CPU, memory, or ephemeral storage) on any available node, causing the scheduler to leave the pod unscheduled. This is confirmed by running 'kubectl describe pod web-frontend' and checking the 'Events' section for 'FailedScheduling' messages.

Answer

The container image does not exist

Answer

The pod's readiness probe is failing

Answer

The pod's liveness probe is failing