KCNA Exam Simulation 1 — 100 Questions

Question 1

Match each Kubernetes resource to its primary purpose.

Question 2

Match each Kubernetes security concept to its definition.

Question 3

A team observes that a Pod is stuck in CrashLoopBackOff. The Pod runs a single container with an entrypoint that exits with non-zero code after a few seconds. The team wants to inspect the container's logs to understand why it is crashing. Which command should they use?

Accepted Answer

kubectl logs --previous. The `kubectl logs --previous` command retrieves the logs from the previous instance of a crashed container. Since the Pod is in CrashLoopBackOff, the current container has already exited, and the `--previous` flag accesses the logs of the last terminated container, which contains the crash output (e.g., the non-zero exit code and error messages). This is the direct way to see why the entrypoint failed.

Answer

kubectl get pods

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kubectl describe pod <pod-name>

Answer

kubectl exec -it <pod-name> -- sh

Question 4

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.. Option C is correct: Secrets should be used for sensitive data like API keys. They are base64 encoded and can be mounted as env vars. Option A is wrong because ConfigMaps are for non-sensitive data. Option B is wrong because storing secrets in plaintext in the image is insecure. Option D is wrong because storing secrets in annotations is not designed for that purpose and is insecure.

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 5

A company is adopting a GitOps workflow for their Kubernetes deployments. They want to ensure that the cluster state always matches the desired state defined in a Git repository. Which tool is specifically designed for this purpose?

Accepted Answer

Argo CD. Argo CD is a declarative, GitOps continuous delivery tool specifically designed for Kubernetes that automatically synchronizes the live cluster state with the desired state defined in a Git repository. It continuously monitors the cluster and Git, applying any drift to ensure the cluster matches the repository, which is the core requirement of a GitOps workflow.

Answer

Helm

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Kustomize

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Prometheus

Question 6

Match each Kubernetes networking concept to its description.

Question 7

A DevOps team notices that a microservice is returning 503 errors intermittently. The service runs in Kubernetes and uses a liveness probe. The team wants to understand the root cause without restarting the pod. Which observability approach should they use first?

Accepted Answer

Query Prometheus for kubelet metrics on probe successes and failures. Option B is correct because Prometheus can scrape kubelet metrics that expose liveness probe success and failure counts directly, allowing the team to see if the probe is failing without restarting the pod. This approach provides historical data on probe behavior, which is essential for diagnosing intermittent 503 errors that stem from the kubelet restarting the container when the liveness probe fails. Unlike other options, it does not require modifying the application or restarting the pod, and it directly surfaces the root cause if the probe is the issue.

Answer

Use kubectl describe pod to check recent events

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Increase log verbosity in the application to capture all requests

Answer

Enable distributed tracing across the service mesh

Question 8

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

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Blue/Green

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Recreate

Question 9

A cluster has a node with the taint 'node-role.kubernetes.io/control-plane:NoSchedule'. A pod must be scheduled on this node for a special workload. Which action is required?

Accepted Answer

Add a toleration to the pod spec.. Option C is correct because a taint on a node causes the scheduler to avoid placing pods on that node unless the pod explicitly tolerates the taint. By adding a toleration in the pod spec that matches the taint key, effect, and optionally the value, the pod becomes eligible to be scheduled on the tainted node. This is the standard Kubernetes mechanism for allowing pods to run on control-plane or other specially tainted nodes.

Answer

Use a nodeSelector to select the node.

Answer

Remove the taint from the node.

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Use podAffinity to attract the pod to the node.

Question 10

A team wants to minimize downtime during a Deployment rollout. Which strategy ensures that new pods are created before old pods are terminated?

Accepted Answer

Set strategy type to 'RollingUpdate' with maxSurge=1, maxUnavailable=0.. Option C is correct because setting `maxSurge=1` and `maxUnavailable=0` in a RollingUpdate strategy ensures that one additional pod is created above the desired replica count before any existing pod is terminated. This guarantees zero downtime by maintaining full capacity during the rollout, as new pods become ready before old ones are removed.

Answer

Set strategy type to 'Recreate'.

Answer

Set strategy type to 'RollingUpdate' with maxSurge=0, maxUnavailable=1.

Answer

Set strategy type to 'RollingUpdate' with maxSurge=1, maxUnavailable=1.

Question 11

An administrator notices that a pod in a Deployment is stuck in CrashLoopBackOff. The pod logs show 'Error: failed to start container: exec: "app": executable file not found in $PATH'. What is the most likely cause?

Accepted Answer

The container image does not contain the binary specified in the pod's command field. The error 'exec: "app": executable file not found in $PATH' indicates that the container image does not contain the binary or script specified in the pod's command field (e.g., `command: ["app"]`). This typically happens when the image is built without the expected executable, the command path is incorrect, or the image tag points to a different version. The container fails to start because the runtime cannot locate the entrypoint.

Answer

The image registry credentials are missing

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The liveness probe is misconfigured and killing the container

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The container is running as a non-root user without proper permissions

Question 12

An administrator needs to ensure that Pods from two different Deployments cannot communicate with each other. Which Kubernetes resource should be used?

Accepted Answer

NetworkPolicy. NetworkPolicy is the correct resource because it acts as a firewall for Kubernetes Pods, controlling ingress and egress traffic at the IP address and port level using layer 3/4 rules. By applying a NetworkPolicy that denies all traffic between the Pods of the two Deployments (e.g., using podSelector and ingress/egress rules with an empty `from` or `to` block), the administrator can enforce network isolation. This is the native Kubernetes mechanism for restricting Pod-to-Pod communication within a cluster.

Answer

RBAC Role

Answer

PodSecurityPolicy

Answer

ResourceQuota

Question 13

Which THREE are key benefits of using a service mesh in a cloud-native architecture? (Choose 3)

Accepted Answer

Mutual TLS (mTLS) encryption between services.. Option B is correct because a service mesh, such as Istio or Linkerd, transparently enables mutual TLS (mTLS) encryption between service sidecar proxies without requiring application code changes. This ensures all inter-service communication is encrypted and authenticated, which is a core security benefit in a zero-trust cloud-native architecture.

Answer

Persistent storage management for stateful applications.

Answer

Automatic horizontal scaling of pods.

Question 14

Match each cloud native concept to its definition.

Question 15

A pod is running but you need to view the contents of a file '/var/log/app.log' inside the container to debug an issue. Which kubectl command allows you to do this without modifying the pod?

Accepted Answer

kubectl exec pod-name -- cat /var/log/app.log. Option C is correct because `kubectl exec pod-name -- cat /var/log/app.log` runs the `cat` command inside the container without modifying the pod or its state. This allows you to view the file contents directly from the container's filesystem, which is essential for debugging when the application logs are not written to stdout/stderr and thus not accessible via `kubectl logs`.

Answer

kubectl logs pod-name -c container-name --tail=100

Answer

kubectl cp pod-name:/var/log/app.log -

Answer

kubectl attach pod-name

Question 16

When using a Service of type ClusterIP, how do pods reach the service?

Accepted Answer

Via the service's cluster IP and port. A Service of type ClusterIP exposes a stable virtual IP (the cluster IP) and port within the cluster. Pods reach the Service by sending traffic to this cluster IP and port, which is then load-balanced by kube-proxy (using iptables, IPVS, or eBPF rules) to one of the backing pod endpoints. This is the default and most fundamental Service type in Kubernetes.

Answer

Via the node's IP address and a high port

Answer

Via an external load balancer

Answer

Directly via the pod's IP address

Question 17

A Service of type ClusterIP is created for a Deployment, but Pods in other namespaces cannot reach it. What is the most likely cause?

Accepted Answer

The Pods in other namespaces are using the short Service name without the namespace suffix. The most likely cause is that Pods in other namespaces are using the short Service name (e.g., `my-service`) without appending the namespace suffix (e.g., `my-service.other-namespace.svc.cluster.local`). Kubernetes DNS resolves short names only within the same namespace; cross-namespace resolution requires the fully qualified domain name (FQDN) or at least the `..svc` form. Without this, the DNS lookup fails, making the Service unreachable from other namespaces.

Answer

NetworkPolicies are blocking cross-namespace traffic

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The Service is not publishing the correct port

Answer

The Service selector does not match the Pod labels

Question 18

What is the primary purpose of a Kubernetes Service?

Accepted Answer

To provide a stable network endpoint for a set of Pods. A Service provides a stable endpoint for a set of Pods, enabling discovery and load balancing across them.

Answer

To manage rolling updates of Pods

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To schedule Pods onto Nodes

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To store configuration data for Pods

Question 19

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

Accepted Answer

Secret. Secrets are designed to store sensitive data, such as passwords, and can be exposed to Pods via environment variables or volumes.

Answer

PersistentVolume

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ConfigMap

Answer

ServiceAccount

Question 20

Two pods, 'app-v1' and 'app-v2', both have a label 'app: myapp'. A Service 'my-service' has a selector 'app: myapp'. How many endpoints will the Service initially have?

Accepted Answer

2. Option A is correct because the Service's selector 'app: myapp' matches both pods 'app-v1' and 'app-v2', which both carry the label 'app: myapp'. The Service controller automatically creates endpoints for all pods matching the selector, regardless of their readiness state, unless a headless service or custom endpoint logic is involved. Initially, both pods are considered ready by default (unless a readiness probe fails), so the Service will have two endpoints.

Answer

1

Answer

0

Answer

Depends on pod readiness