Kubernetes & Orchestration Essentials (CKA Prep) Flashcards

Question 1

What is Kubernetes?

Accepted Answer

Kubernetes is an open-source container orchestration platform designed to automate the deployment, scaling, and management of containerized applications. It groups containers that make up an application into logical units for easy management and discovery.

Question 2

What is a Pod in Kubernetes?

Accepted Answer

A `Pod` is the smallest deployable unit in Kubernetes. It represents a single instance of a running process in your cluster. A Pod encapsulates one or more containers (e.g., Docker containers), storage resources, a unique network IP, and options that govern how the containers should run.

Question 3

Explain the purpose of a Kubernetes Deployment.

Accepted Answer

A `Deployment` provides declarative updates for Pods and ReplicaSets. You describe a desired state in a Deployment, and the Deployment Controller changes the actual state to the desired state at a controlled rate. It's used for stateless applications, managing rollouts, rollbacks, and scaling.

Question 4

What is a Kubernetes Service?

Accepted Answer

A `Service` is an abstract way to expose an application running on a set of Pods as a network service. Services enable network access to a group of Pods, providing a stable IP address and DNS name, even as Pods are created, deleted, or moved.

Question 5

What is Kubernetes Ingress?

Accepted Answer

`Ingress` exposes HTTP and HTTPS routes from outside the cluster to services within the cluster. It provides external access to your services with features like load balancing, SSL termination, and name-based virtual hosting, typically managed by an Ingress Controller.

Question 6

What is a Kubernetes Namespace?

Accepted Answer

A `Namespace` provides a mechanism for isolating groups of resources within a single Kubernetes cluster. It's used to divide cluster resources between multiple users or teams, providing a scope for names and preventing naming collisions.

Question 7

What is a Kubernetes Node?

Accepted Answer

A `Node` is a worker machine in Kubernetes, previously known as a minion. Each Node has the necessary services to run Pods, including the container runtime (e.g., containerd), `kubelet` (an agent for the master), and `kube-proxy` (network proxy).

Question 8

List the key components of the Kubernetes Control Plane (Master).

Accepted Answer

The Kubernetes Control Plane consists of:
*   `kube-apiserver`: Exposes the Kubernetes API.
*   `etcd`: Consistent and highly-available key-value store for all cluster data.
*   `kube-scheduler`: Watches for newly created Pods and assigns them to Nodes.
*   `kube-controller-manager`: Runs controller processes (e.g., Node, Replication, Endpoints, Service Account & Token Controllers).
*   `cloud-controller-manager` (optional): Interacts with underlying cloud providers.

Question 9

How do you list all Pods in the current namespace using `kubectl`?

Accepted Answer

Use the command: `kubectl get pods`
To see Pods across all namespaces, use: `kubectl get pods --all-namespaces` or `kubectl get pods -A`.

Question 10

How can you get detailed information about a specific Pod using `kubectl`?

Accepted Answer

Use the command: `kubectl describe pod <pod-name>`
This command provides extensive details including events, labels, annotations, status, and resource usage.

Question 11

What `kubectl` command is used to create resources from a YAML file?

Accepted Answer

Use the command: `kubectl create -f <file.yaml>`
This command is typically used for one-time resource creation. For declarative management and updates, `kubectl apply` is preferred.

Question 12

What is the primary difference between `kubectl create -f` and `kubectl apply -f`?

Accepted Answer

*   `kubectl create -f`: Creates a resource. If the resource already exists, it will fail.
*   `kubectl apply -f`: Creates a resource if it doesn't exist, or updates it if it does. It's idempotent and preferred for declarative configuration management as it tracks changes.

Question 13

How do you delete a specific Pod or a resource defined in a YAML file using `kubectl`?

Accepted Answer

* To delete a specific Pod: `kubectl delete pod ` * To delete resources defined in a YAML file: `kubectl delete -f `

Question 14

How do you view the logs of a running container within a Pod using `kubectl`?

Accepted Answer

Use the command: `kubectl logs ` To follow logs in real-time: `kubectl logs -f ` If a Pod has multiple containers, specify the container name: `kubectl logs -c `

Question 15

How can you execute a command inside a running container within a Pod using `kubectl`?

Accepted Answer

Use the command: `kubectl exec -it -- ` For an interactive shell: `kubectl exec -it -- bash` (or `sh`) The `-i` flag keeps stdin open, and `-t` allocates a pseudo-TTY.

Question 16

List and briefly describe the main Pod Lifecycle Phases.

Accepted Answer

*   `Pending`: The Pod has been accepted by the Kubernetes cluster, but one or more of the container images has not been created.
*   `Running`: The Pod has been bound to a node, and all of the containers have been created. At least one container is still running, or is in the process of starting or restarting.
*   `Succeeded`: All containers in the Pod have terminated successfully, and will not restart.
*   `Failed`: All containers in the Pod have terminated, and at least one container has terminated in failure.
*   `Unknown`: For some reason, the state of the Pod could not be obtained.

Question 17

Explain Pod Lifecycle Hooks: `PostStart` and `PreStop`.

Accepted Answer

Pod Lifecycle Hooks are actions triggered at specific points in a container's lifecycle:
*   `PostStart`: Executed immediately after a container is created. It's useful for setup tasks like database initialization.
*   `PreStop`: Executed just before a container is terminated due to an API request or management event (e.g., scaling down, deletion). It's useful for graceful shutdown, like draining connections.

Question 18

Describe the `ClusterIP` Service type.

Accepted Answer

`ClusterIP` is the default Service type. It exposes the Service on an internal IP address within the cluster. This Service is only reachable from within the cluster. It's ideal for internal communication between different services in your application.

Question 19

Describe the `NodePort` Service type.

Accepted Answer

`NodePort` exposes the Service on each Node's IP at a static port (the `NodePort`). A `ClusterIP` Service is automatically created, and the NodePort Service routes to it. This allows external traffic to reach the Service by accessing `:`.

Question 20

Describe the `LoadBalancer` Service type.

Accepted Answer

`LoadBalancer` exposes the Service externally using a cloud provider's load balancer. It automatically provisions an external load balancer, which routes traffic to the NodePort Service, and then to the Pods. This type is only available when running on a supported cloud provider.

Question 21

What is a Kubernetes PersistentVolume (PV)?

Accepted Answer

A `PersistentVolume` (PV) is an abstract storage resource in the cluster, provisioned by an administrator or dynamically provisioned using Storage Classes. It's a piece of storage in the cluster that has been provisioned by an administrator. It is a resource in the cluster just like a Node is a cluster resource.

Question 22

What is a Kubernetes PersistentVolumeClaim (PVC)?

Accepted Answer

A `PersistentVolumeClaim` (PVC) is a request for storage by a user. It consumes PV resources. A PVC specifies the desired size, access modes (e.g., ReadWriteOnce, ReadOnlyMany), and optionally a StorageClass. Kubernetes binds a PVC to an available PV that meets its requirements.

Question 23

Explain the purpose of a Kubernetes ConfigMap.

Accepted Answer

A `ConfigMap` is an API object used to store non-sensitive configuration data in key-value pairs. It allows you to decouple configuration artifacts from image content to keep containerized applications portable. Pods can consume ConfigMaps as environment variables, command-line arguments, or as files in a volume.

Question 24

Explain the purpose of a Kubernetes Secret.

Accepted Answer

A `Secret` is an API object used to store sensitive information, such as passwords, OAuth tokens, and SSH keys. It's similar to a ConfigMap but is designed for confidential data. Secrets are base64 encoded by default (not encrypted at rest without additional configuration) and can be consumed by Pods as environment variables or mounted as files.

Question 25

What is RBAC in Kubernetes and why is it important?

Accepted Answer

`RBAC` (Role-Based Access Control) is a method of regulating access to computer or network resources based on the roles of individual users within an enterprise. In Kubernetes, RBAC allows you to define who can do what to which resources (e.g., "user 'dev-team' can 'get' and 'list' 'pods' in 'development' namespace"). It's crucial for securing your cluster by enforcing the principle of least privilege.

Kubernetes & Orchestration Essentials (CKA Prep)

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