CKA Cluster Architecture, Installation & Configuration — Timed 10 Questions

Question 1

A company wants to install Kubernetes on a set of bare-metal servers with no existing orchestration tools. They need a solution that supports high availability for the control plane and uses etcd operators for cluster management. Which tool should they use?

Accepted Answer

kubeadm. kubeadm is the correct choice because it is the official Kubernetes tool for bootstrapping production-grade clusters on bare-metal servers, supporting high availability (HA) for the control plane via stacked or external etcd topologies. It integrates with etcd operators (e.g., etcdadm or the etcd-operator project) for cluster management, allowing automated etcd cluster lifecycle operations. Other tools either lack HA control plane support, are not designed for bare-metal, or do not use etcd operators.

Answer

kube-spray

Answer

minikube

Answer

kops

Question 2

A DevOps engineer notices that the kubelet on a node is unable to register with the Kubernetes API server. The kubelet logs show 'Failed to get bootstrap CA certificate' and the node is not yet part of the cluster. What is the most likely cause?

Accepted Answer

The bootstrap token used for TLS bootstrapping has expired.. The bootstrap token used for TLS bootstrapping has expired. During the TLS bootstrap process, the kubelet uses a limited-time bootstrap token to authenticate with the API server and request a client certificate. If the token expires before the kubelet completes registration, the kubelet will fail to obtain the bootstrap CA certificate and cannot join the cluster, as indicated by the error 'Failed to get bootstrap CA certificate'.

Answer

The kubelet configuration file has incorrect node IP.

Answer

The node's RBAC permissions are misconfigured.

Answer

The API server is not running.

Question 3

An administrator needs to upgrade the kube-apiserver on a control plane node from version 1.22.0 to 1.23.0. Which of the following is the correct order of steps?

Accepted Answer

Drain node, upgrade kubeadm, upgrade kubelet, uncordon node.. Option B is correct because when upgrading the kube-apiserver, the standard workflow is to first drain the node to evict pods, then upgrade kubeadm (which manages the control plane components), then upgrade kubelet (which runs on the node), and finally uncordon the node to make it schedulable again. This sequence ensures that the node is safely taken out of service before any changes are made, and that the upgrade tools are updated before the components they manage.

Answer

Upgrade kubelet, upgrade kubeadm, drain node, uncordon node.

Answer

Upgrade kubeadm, drain node, upgrade kubelet, uncordon node.

Answer

Upgrade kubeadm, upgrade kubelet, drain node, uncordon node.

Question 4

A Kubernetes cluster has been running for months. Recently, some pods are reporting 'FailedScheduling' due to insufficient memory. The administrator wants to add a new node with 32GB RAM. However, after joining the node, the new node shows 'NotReady' and the kubelet logs indicate 'Failed to update node status: context deadline exceeded'. What is the most likely cause?

Accepted Answer

There is a network connectivity issue between the new node and the control plane.. The 'context deadline exceeded' error in the kubelet logs indicates that the kubelet on the new node is unable to communicate with the API server within the expected timeout. This is typically caused by network connectivity issues between the node and the control plane, such as firewall rules, incorrect DNS resolution, or a broken CNI plugin. Without successful node-to-API-server communication, the kubelet cannot post its status, leaving the node in 'NotReady' state.

Answer

The kubelet is not configured with the correct node IP.

Answer

The new node does not have enough disk space for container images.

Answer

The API server is overloaded and cannot handle the node update request.

Question 5

A cluster administrator has configured a PodSecurityPolicy (PSP) that requires all pods to run with read-only root filesystem. However, a newly deployed pod is failing to start with the error 'container has runAsNonRoot and image will run as root'. The PSP is designed to prevent running as root. What is the most likely cause?

Accepted Answer

The container image is configured to run as root user.. The error message 'container has runAsNonRoot and image will run as root' indicates that the PodSecurityPolicy (PSP) is configured with `runAsNonRoot: true`, but the container image itself is built to run as the root user (UID 0). The PSP enforces that the container must not run as root, but the image's default user is root, causing the admission controller to reject the pod. Option C correctly identifies this mismatch as the most likely cause.

Answer

The PodSecurityPolicy admission controller is not enabled.

Answer

The PSP is not set to enforce read-only root filesystem.

Answer

The PSP is not being applied to the pod's service account.

Question 6

An administrator is tasked with setting up a new Kubernetes cluster using kubeadm. They have two nodes: one control plane and one worker. After initializing the control plane with 'kubeadm init', the worker node fails to join with the error 'error execution phase preflight: [preflight] Some fatal errors occurred: [ERROR CRI]: container runtime is not running'. What should the administrator check first?

Accepted Answer

Ensure that containerd is installed and running on the worker node.. The error 'container runtime is not running' on the worker node indicates that the CRI (Container Runtime Interface) implementation, typically containerd, is not active. Since kubelet relies on a running container runtime to manage pods, the administrator must first check that containerd is installed and running on the worker node using commands like 'systemctl status containerd' or 'systemctl start containerd'.

Answer

Verify that the control plane node is healthy.

Answer

Check if the join token has expired.

Answer

Install a network plugin like Calico on the control plane.

Question 7

A team is configuring etcd for a multi-node Kubernetes cluster. They want to ensure that etcd data is encrypted at rest. Which approach should they use?

Accepted Answer

Create an EncryptionConfiguration resource specifying a provider like 'aescbc' and configure the kube-apiserver with --encryption-provider-config.. Option B is correct because Kubernetes supports encrypting secrets and other resources at rest via an EncryptionConfiguration object, which is passed to the kube-apiserver using the --encryption-provider-config flag. This mechanism encrypts data before it is written to etcd, ensuring that even if the etcd storage is compromised, the data remains unreadable without the encryption key.

Answer

Use LUKS to encrypt the disk partition where etcd data is stored.

Answer

Use TLS certificates to encrypt communication between etcd and the API server.

Answer

Configure etcd to use encryption at rest by setting --experimental-encryption-provider.

Question 8

A cluster is running on a cloud provider that supports load balancers. An administrator needs to expose a service externally using a cloud load balancer. However, the service remains in 'Pending' state. The cloud provider requires the cluster to be configured with the correct cloud provider flag. Which kube-controller-manager flag is required for this integration?

Accepted Answer

--cloud-provider. The `--cloud-provider` flag on the kube-controller-manager tells Kubernetes which cloud provider integration to use (e.g., `aws`, `gce`, `azure`). Without this flag set to the correct provider, the cloud controller manager cannot provision a load balancer for a Service of type LoadBalancer, leaving it in 'Pending' state because the external IP allocation never completes.

Answer

--cloud-controller-manager

Answer

--configure-cloud-routes

Answer

--cloud-config

Question 9

During a 'kubeadm init', the administrator sees the message 'Your Kubernetes control-plane has been initialized successfully!' but the 'kubectl get nodes' shows the control plane node as 'NotReady'. What is the most likely missing step?

Accepted Answer

Install a CNI plugin such as Calico or Flannel.. The 'NotReady' status indicates that the kubelet on the control plane node is running but cannot report readiness because the node's network is not configured. A CNI plugin (e.g., Calico, Flannel, Weave) must be installed to set up the pod network, which is required for the kubelet to register the node as 'Ready'. Without a CNI plugin, the node's network conditions remain unmet, and the control plane cannot function properly.

Answer

Generate a join token for worker nodes.

Answer

Copy the kubeconfig to the user's home directory.

Answer

Check that the kubelet is running on the control plane node.

Question 10

Which TWO of the following are valid commands to upgrade a kubeadm cluster from version 1.22.x to 1.23.x on the control plane node? Assume the node is already drained.

Accepted Answer

kubeadm upgrade apply v1.23.0. Option A is correct because `kubeadm upgrade apply v1.23.0` is the explicit command to upgrade the control plane to a specific version (v1.23.0) in a kubeadm cluster. It validates the upgrade path, uploads the new configuration, and applies the upgrade to the control plane components. The node is already drained, so this command proceeds directly with the upgrade.

Answer

kubeadm upgrade node

Answer

kubeadm upgrade plan v1.23.0

Answer

kubeadm upgrade diff