KCNA Kubernetes Fundamentals Practice Test 25 — 15 Questions

Question 1

You have a Service of type ClusterIP named 'my-svc' in the 'default' namespace. A Pod in the same cluster wants to reach this Service using DNS. What is the fully qualified domain name (FQDN) that resolves to the Service's cluster IP?

Accepted Answer

my-svc.default.svc.cluster.local. Option A is correct because the standard DNS naming convention for a Kubernetes Service is `..svc.cluster.local`. This FQDN resolves to the ClusterIP of the Service, allowing Pods to discover and communicate with the Service using DNS. The `svc` subdomain is a fixed part of the cluster domain, and `cluster.local` is the default cluster domain suffix.

Answer

my-svc.default.cluster.local

Answer

default.my-svc.svc.cluster.local

Answer

my-svc.svc.default.cluster.local

Question 2

Which two of the following are valid ways to expose a set of Pods to external traffic?

Accepted Answer

Create a Service of type NodePort. NodePort and LoadBalancer are two Service types that expose applications externally.

Answer

Use a ConfigMap to expose the Pods

Answer

Create an Ingress resource without a Service

Answer

Create a Service of type ClusterIP

Question 3

Which two of the following are valid ways to set resource constraints on a container in a Pod spec?

Accepted Answer

Specify 'resources.limits.memory' for maximum memory. Option B is correct because 'resources.limits.memory' is the valid Kubernetes field to set the maximum amount of memory a container can use. When a container exceeds this limit, it may be terminated or OOM-killed by the kubelet. This is a core concept in Kubernetes resource management for ensuring predictable application behavior.

Answer

Specify 'resources.guarantees.cpu' for CPU guarantees

Answer

Specify 'resources.min.memory' for minimum memory

Answer

Specify 'resources.max.cpu' for CPU limits

Question 4

Which three of the following are true about etcd in Kubernetes?

Accepted Answer

etcd stores all cluster state, including Pods, ConfigMaps, and Secrets. Option A is correct because etcd is the primary datastore for Kubernetes, storing all cluster state including objects like Pods, ConfigMaps, and Secrets. This ensures that the Kubernetes API server has a consistent, authoritative source of truth for the entire cluster.

Answer

etcd is a relational database

Answer

etcd can be used as a message queue

Question 5

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 6

Which kubectl command would you use to view detailed information about a specific pod, including events and container status?

Accepted Answer

kubectl describe pod . Option D is correct because `kubectl describe pod ` provides a comprehensive view of a pod's metadata, spec, status, conditions, container resource usage, and a chronological list of events (e.g., scheduling, pulling images, container restarts). This command aggregates information from the Kubernetes API server, including the pod's current state and lifecycle events, which is essential for debugging pod failures or unexpected behavior.

Answer

kubectl explain pod

Answer

kubectl get pod <pod-name>

Answer

kubectl logs pod <pod-name>

Question 7

You have a Deployment named 'web-app' that manages 3 replicas. You need to update the container image from version 1.0 to 2.0 with zero downtime. Which Kubernetes feature is designed to handle this automatically when you update the Deployment's pod template?

Accepted Answer

Rolling update strategy in the Deployment. The correct answer is B because a Deployment's default update strategy is 'RollingUpdate', which automatically replaces old Pods with new ones in a controlled manner, ensuring zero downtime by incrementally scaling down old replicas and scaling up new replicas. When you update the container image in the Deployment's pod template, Kubernetes triggers a rolling update that maintains the desired number of replicas throughout the process.

Answer

ReplicationController

Answer

DaemonSet

Answer

StatefulSet's onDelete strategy

Question 8

A pod in the 'production' namespace is in a CrashLoopBackOff state. The pod has been running successfully for several days. You run 'kubectl describe pod app-pod -n production' and see the message: 'OOMKilled'. What is the MOST appropriate action to resolve this issue?

Accepted Answer

Increase the memory limit in the pod's container resource specification. The 'OOMKilled' status indicates the pod's container was terminated by the Linux kernel Out-of-Memory (OOM) killer because it exceeded its configured memory limit. Since the pod ran successfully for days, this suggests a gradual memory leak or increased workload demand. Increasing the memory limit in the pod's container resource specification allows the container to use more memory before being killed, directly addressing the root cause.

Answer

Increase the CPU request for the container

Answer

Delete the namespace and redeploy all workloads

Answer

Delete and recreate the pod to clear the crash loop

Question 9

Which Kubernetes resource provides stable network endpoints for a set of pods, enabling service discovery and load balancing?

Accepted Answer

Service. A Service is the correct Kubernetes resource because it provides a stable virtual IP (ClusterIP) and DNS name that persists independently of pod lifecycles, enabling reliable service discovery and client-side load balancing across a set of pods selected by labels. This abstraction decouples clients from ephemeral pod IPs, ensuring traffic is routed to healthy pods via kube-proxy and iptables/IPVS rules.

Answer

NetworkPolicy

Answer

Ingress

Answer

EndpointSlice

Question 10

You want to deploy a stateless web application that should maintain 5 running instances at all times. You need to support rolling updates and rollbacks. Which Kubernetes resource is most appropriate?

Accepted Answer

Deployment. A Deployment manages a ReplicaSet and provides declarative updates, rolling updates, and rollback capabilities, making it ideal for stateless applications.

Answer

DaemonSet

Answer

ReplicaSet

Answer

StatefulSet

Question 11

A user reports that their application's DNS resolution is failing for a Service named 'my-service' in the same namespace. They are able to reach the Service by its cluster IP. Which of the following is the most likely cause?

Accepted Answer

The CoreDNS pod is not running or misconfigured. Option C is correct because DNS resolution for a Service in the same namespace relies on CoreDNS, which is the cluster DNS provider in Kubernetes. If CoreDNS is not running or misconfigured, DNS queries for the Service name (e.g., 'my-service') will fail, even though the Service is reachable via its cluster IP. The user's ability to reach the Service by IP confirms that kube-proxy and networking are functional, isolating the issue to DNS resolution.

Answer

The application container is using an incorrect DNS policy

Answer

The kube-proxy is misconfigured on the node

Answer

The Service is of type ExternalName

Question 12

Which component runs on every worker node and is responsible for ensuring that containers are running in a pod as specified in the PodSpec?

Accepted Answer

kubelet. The kubelet is the primary node agent that runs on every worker node in a Kubernetes cluster. It is responsible for ensuring that containers described in a PodSpec are running and healthy, by interacting with the container runtime (e.g., containerd, CRI-O) to create, start, and monitor pods. The kubelet does not manage containers that were not created by Kubernetes.

Answer

container runtime

Answer

kube-proxy

Answer

kube-scheduler

Question 13

Which Kubernetes primitive is the smallest and simplest unit in the Kubernetes object model that you can create or deploy?

Accepted Answer

Pod. A Pod is the smallest deployable unit in Kubernetes, representing a single instance of a running process in the cluster.

Answer

ReplicaSet

Answer

Deployment

Answer

Container

Question 14

You have a Kubernetes cluster with multiple namespaces. You need to allow communication only from pods with label 'app: frontend' to pods with label 'app: backend' in the same namespace. Which resource should you use?

Accepted Answer

NetworkPolicy. A NetworkPolicy is used to control ingress and egress traffic to pods based on labels and other selectors. It can be used to restrict communication between pods.

Answer

RBAC Role

Answer

PodSecurityPolicy

Answer

Service

Question 15

You run 'kubectl get pods' and see a pod in 'Pending' state for over 5 minutes. You describe the pod and see '0/1 nodes are available: 1 Insufficient memory'. What is the most likely cause?

Accepted Answer

The pod's memory request is larger than any node's allocatable memory. The '0/1 nodes are available: 1 Insufficient memory' message indicates that the Kubernetes scheduler could not place the pod because no node has enough allocatable memory to satisfy the pod's memory request. Option B is correct because the pod's memory request exceeds the available memory on any node, causing the pod to remain in Pending state indefinitely until sufficient resources become available.

Answer

The container image is too large

Answer

The pod has a liveness probe that is failing

Answer

The kubelet on the node is not running