CKA - Certified Kubernetes Administrator: Workloads & Networking Flashcards

Question 1

What is the primary function of a `PersistentVolumeClaim` (PVC)?

Accepted Answer

A `PersistentVolumeClaim` is a request for storage by a user. It consumes PV resources. Pods request storage by specifying a PVC in their `volume` definition.

Question 2

How do you imperatively create a Pod named `my-nginx-pod` using the `nginx` image?

Accepted Answer

Use the `kubectl run` command with `--restart=Never` for a standalone Pod:
`kubectl run my-nginx-pod --image=nginx --restart=Never`

Question 3

What `PodSpec` field defines the container image to use?

Accepted Answer

The `image` field within the `containers` array. Example:
```yaml
apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: my-container
    image: nginx:latest
```

Question 4

How do you define resource requests and limits for a container in a `PodSpec`?

Accepted Answer

Using the `resources` field within a container definition:
```yaml
resources:
  requests:
    memory: "64Mi"
    cpu: "250m"
  limits:
    memory: "128Mi"
    cpu: "500m"
```

Question 5

Explain the purpose of a `LivenessProbe` in a Pod.

Accepted Answer

A `LivenessProbe` checks if a container is still running and healthy. If it fails, Kubernetes restarts the container. This ensures applications don't get stuck in a broken state.

Question 6

How do you imperatively create a Deployment named `my-app-deployment` with 3 replicas using the `my-app:v1` image?

Accepted Answer

`kubectl create deployment my-app-deployment --image=my-app:v1 --replicas=3`

Question 7

What is the primary function of a `PersistentVolume` (PV)?

Accepted Answer

A `PersistentVolume` is an abstract storage resource in a Kubernetes cluster, provisioned by an administrator or dynamically. It represents a piece of storage (e.g., NFS, iSCSI, hostPath) that can be claimed by Pods.

Question 8

How do you define a `hostPath` PersistentVolume?

Accepted Answer

```yaml
apiVersion: v1
kind: PersistentVolume
metadata:
  name: my-hostpath-pv
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: "/mnt/data"
```

Question 9

How do you mount a `PersistentVolumeClaim` named `my-pvc` into a Pod at path `/data`?

Accepted Answer

In the Pod's `spec.volumes` and `spec.containers.volumeMounts`:
```yaml
spec:
  volumes:
  - name: my-storage
    persistentVolumeClaim:
      claimName: my-pvc
  containers:
  - name: my-container
    image: busybox
    volumeMounts:
    - name: my-storage
      mountPath: "/data"
```

Question 10

What are the three main types of Kubernetes Services and their primary use cases?

Accepted Answer

1. `ClusterIP`: Exposes the Service on an internal IP in the cluster. Only reachable from within the cluster. Default type. 2. `NodePort`: Exposes the Service on each Node's IP at a static port (the `NodePort`). Makes the Service accessible from outside the cluster using `:`. 3. `LoadBalancer`: Exposes the Service externally using a cloud provider's load balancer. Only available with cloud providers that support it.

Question 11

How do you imperatively expose a Deployment named `my-web-app` as a `NodePort` Service on port 80?

Accepted Answer

`kubectl expose deployment my-web-app --type=NodePort --port=80`

Question 12

What is an `Ingress` resource in Kubernetes?

Accepted Answer

An `Ingress` resource manages external access to services in a cluster, typically HTTP/HTTPS. It provides HTTP routing, SSL termination, and name-based virtual hosting. It requires an `Ingress Controller` to be running.

Question 13

What is the role of a CNI (Container Network Interface) plugin in Kubernetes?

Accepted Answer

CNI plugins are responsible for configuring network interfaces for Pods. They ensure that Pods can communicate with each other across nodes and with external services, assigning IP addresses and setting up routing rules. Examples include Calico, Flannel, Weave Net.

Question 14

What is a `Role` in Kubernetes RBAC?

Accepted Answer

A `Role` is an RBAC object that defines a set of permissions within a specific namespace. It grants access to resources (e.g., `pods`, `deployments`) and verbs (e.g., `get`, `list`, `create`, `delete`).

Question 15

What is a `ClusterRole` in Kubernetes RBAC?

Accepted Answer

A `ClusterRole` is similar to a `Role` but is non-namespaced. It can grant permissions to cluster-scoped resources (e.g., `nodes`), or to namespaced resources across all namespaces.

Question 16

How do you bind a `Role` named `pod-reader` to a `ServiceAccount` named `my-sa` in the `default` namespace?

Accepted Answer

Using a `RoleBinding`:
```yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: read-pods-binding
  namespace: default
subjects:
- kind: ServiceAccount
  name: my-sa
  namespace: default
roleRef:
  kind: Role
  name: pod-reader
  apiGroup: rbac.authorization.k8s.io
```

Question 17

What command is used to take a snapshot of the `etcd` database?

Accepted Answer

`ETCDCTL_API=3 etcdctl snapshot save <snapshot-file-path>`
(Remember to specify `--endpoints` if not default, and TLS certs/keys for secure clusters.)

Question 18

How do you restore an `etcd` snapshot to a new data directory?

Accepted Answer

`ETCDCTL_API=3 etcdctl snapshot restore --data-dir ` After restoring, ensure the `etcd` static Pod manifest (usually in `/etc/kubernetes/manifests/etcd.yaml`) is updated to point to the new data directory.

Question 19

What `kubectl` command is essential for debugging Pods by viewing their output?

Accepted Answer

`kubectl logs [-c ]`

Question 20

What `kubectl` command provides detailed information about a Kubernetes resource, including events?

Accepted Answer

`kubectl describe

` (e.g., `kubectl describe pod my-pod`)

Question 21

How do you execute a command inside a running container within a Pod?

Accepted Answer

`kubectl exec -it [-c ] -- ` (e.g., `kubectl exec -it my-nginx-pod -- bash`)

Question 22

What is the purpose of `ReadinessProbe` in a Pod?

Accepted Answer

A `ReadinessProbe` checks if a container is ready to serve traffic. If it fails, Kubernetes removes the Pod's IP address from the Service endpoints, preventing traffic from being routed to it until it becomes ready again.

Question 23

How do you scale a Deployment named `my-deployment` to 5 replicas using an imperative command?

Accepted Answer

`kubectl scale deployment my-deployment --replicas=5`

Question 24

What is the default `restartPolicy` for a Pod created by a Deployment?

Accepted Answer

The default `restartPolicy` for Pods managed by a Deployment is `Always`. For standalone Pods created with `kubectl run --restart=Never`, it's `Never`. For Jobs, it's typically `OnFailure` or `Never`.

Question 25

How can you view all events in the current namespace?

Accepted Answer

`kubectl get events` or `kubectl get events --watch` for continuous updates.

CKA - Certified Kubernetes Administrator: Workloads & Networking

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