CKA Cluster Architecture, Installation, and Configuration

Question 1

What is the role of the kube-apiserver in a Kubernetes cluster?

Accepted Answer

It provides an interface for the control plane to communicate with the cluster.

Answer

The kube-apiserver is the front end of the Kubernetes control plane, exposing the Kubernetes API. It acts as the central communication hub, processing REST requests, validating configurations, and enabling all components of the control plane and users to interact with the cluster's resources.

Question 2

Which command initializes a Kubernetes control plane node using kubeadm?

Accepted Answer

kubeadm init

Answer

The `kubeadm init` command is specifically designed to bootstrap a Kubernetes control-plane node. It performs the necessary steps to set up the core components, configure the cluster, and generate the required certificates and configuration files, effectively turning a machine into a Kubernetes control plane.

Question 3

Which component of a Kubernetes cluster stores the configuration data in a key-value store?

Accepted Answer

etcd

Answer

etcd is a distributed, reliable key-value store that Kubernetes uses to store all cluster data, including configuration, state, and metadata. It acts as the cluster's single source of truth, ensuring consistency and availability of the control plane's critical information. Without etcd, the Kubernetes API server would not be able to retrieve or persist the desired state of the cluster.

Question 4

What command is used to apply a Pod network in a Kubernetes cluster after initialization?

Accepted Answer

kubectl apply -f <network-yaml-file>

Answer

After `kubeadm init` initializes the control plane, a Container Network Interface (CNI) plugin must be installed to enable Pod-to-Pod communication. CNI plugins are typically deployed using a YAML manifest, which is applied to the cluster using the `kubectl apply -f` command. This command reads the configuration from the specified YAML file and creates the necessary Kubernetes objects, such as DaemonSets or Deployments, to install the network plugin.

Question 5

What is the purpose of a kube-scheduler in Kubernetes?

Accepted Answer

To allocate resources for Pods across the cluster.

Answer

The `kube-scheduler` is a control plane component responsible for watching newly created Pods that have no assigned node. It selects the best node for each Pod to run on, considering various factors like resource requirements, hardware constraints, policy constraints, and affinity/anti-affinity specifications. Its primary goal is to ensure efficient resource utilization and optimal placement of workloads across the cluster.

(CKA) Certified Kubernetes Administrator Practice Test

(CKA) Certified Kubernetes Administrator Practice Test

CKA Cluster Architecture, Installation, and Configuration