Linux Foundation Linux Foundation Certifications CKA Questions & Answers

• Question 41:

  SIMULATION

  Create a persistent volume with name app-data, of capacity 2Gi and access mode ReadWriteMany. The type of volume is hostPath and its location is /srv/app-data.

  Correct Answer: Check the answer in explanation.

  Persistent Volume A persistent volume is a piece of storage in a Kubernetes cluster. PersistentVolumes are a cluster- level resource like nodes, which don't belong to any namespace. It is provisioned by the administrator and has a particular file size. This way, a developer deploying their app on Kubernetes need not know the underlying infrastructure. When the developer needs a certain amount of persistent storage for their application, the system administrator configures the cluster so that they consume the PersistentVolume provisioned in an easy way. Creating Persistent Volume kind: PersistentVolume apiVersion: v1 metadata: name:app-data spec: capacity: # defines the capacity of PV we are creating storage: 2Gi #the amount of storage we are tying to claim accessModes: # defines the rights of the volume we are creating

  -ReadWriteMany

  hostPath:

  path: "/srv/app-data" # path to which we are creating the volume Challenge

  Create a Persistent Volume named app-data, with access mode ReadWriteMany, storage classname shared, 2Gi of storage capacity and the host path /srv/app-data.

  

  2.

  Save the file and create the persistent volume.

  3.

  View the persistent volume.

  

  

  Our persistent volume status is available meaning it is available and it has not been mounted yet. This status will change when we mount the persistentVolume to a persistentVolumeClaim. PersistentVolumeClaim In a real ecosystem, a system admin will create the PersistentVolume then a developer will create a PersistentVolumeClaim which will be referenced in a pod. A PersistentVolumeClaim is created by specifying the minimum size and the access mode they require from the persistentVolume. Challenge Create a Persistent Volume Claim that requests the Persistent Volume we had created above. The claim should request 2Gi. Ensure that the Persistent Volume Claim has the same storageClassName as the persistentVolume you had previously created. kind: PersistentVolume apiVersion: v1 metadata: name:app-data spec: accessModes:

  -ReadWriteMany resources: requests: storage: 2Gi storageClassName: shared

  2.

  Save and create the pvc njerry191@cloudshell:~ (extreme-clone-2654111)$ kubect1 create -f app-data.yaml persistentvolumeclaim/app-data created

  3.

  View the pvc

  4.

  Let's see what has changed in the pv we had initially created.

  

  

  Our status has now changed from available to bound.

  5. Create a new pod named myapp with image nginx that will be used to Mount the Persistent Volume Claim with the path /var/app/config. Mounting a Claim apiVersion: v1 kind: Pod metadata: creationTimestamp: null name: app-data spec: volumes:

  -name:congigpvc persistenVolumeClaim: claimName: app-data containers:

  -image: nginx name: app volumeMounts:

  -mountPath: "/srv/app-data " name: configpvc

• Question 42:

  SIMULATION

  Given a partially-functioning Kubernetes cluster, identify symptoms of failure on the cluster.

  Determine the node, the failing service, and take actions to bring up the failed service and restore the health of the cluster. Ensure that any changes are made permanently.

  You can ssh to the relevant I nodes (bk8s-master-0 or bk8s-node-0) using:

  [student@node-1] $ ssh

  You can assume elevated privileges on any node in the cluster with the following command:

  [student@nodename] $ | sudo -i

  Correct Answer: Check the answer in explanation.

  solution

  

  

• Question 43:

  SIMULATION

  Configure the kubelet systemd- managed service, on the node labelled with name=wk8s-node-1, to launch a pod containing a single container of Image httpd named webtool automatically. Any spec files required should be placed in the /etc/

  kubernetes/manifests directory on the node.

  You can ssh to the appropriate node using:

  [student@node-1] $ ssh wk8s-node-1

  You can assume elevated privileges on the node with the following command:

  [student@wk8s-node-1] $ | sudo -i

  Correct Answer: Check the answer in explanation.

  

  

  

  

• Question 44:

  SIMULATION For this item, you will have to ssh to the nodes ik8s-master-0 and ik8s-node-0 and complete all tasks on these nodes. Ensure that you return to the base node (hostname: node-1) when you have completed this item. Context

  As an administrator of a small development team, you have been asked to set up a Kubernetes cluster to test the viability of a new application.

  Task

  You must use kubeadm to perform this task. Any kubeadm invocations will require the use of the -- ignore-preflight-errors=all option.

  Configure the node ik8s-master-O as a master node. .

  Join the node ik8s-node-o to the cluster.

  Correct Answer: Check the answer in explanation.

  Solution

  You must use the kubeadm configuration file located at /etc/kubeadm.conf when initializing your cluster.

  You may use any CNI plugin to complete this task, but if you don't have your favourite CNI plugin's manifest URL at hand, Calico is one popular option:

  https://docs.projectcalico.org/v3.14/manifests/calico.yaml Docker is already installed on both nodes and apt has been configured so that you can install the required tools.

• Question 45:

  SIMULATION

  

  Create a snapshot of the etcd instance running at https://127.0.0.1:2379, saving the snapshot to the file path /srv/data/etcd-snapshot.db. The following TLS certificates/key are supplied for connecting to the server with etcdctl:

  1.

  CA certificate: /opt/KUCM00302/ca.crt

  2.

  Client certificate: /opt/KUCM00302/etcd-client.crt

  3.

  Client key: Topt/KUCM00302/etcd-client.key

  Correct Answer: Check the answer in explanation.

  Solution

  

• Question 46:

  SIMULATION

  

  Set the node named ek8s-node-1 as unavailable and reschedule all the pods running on it.

  Correct Answer: Check the answer in explanation.

  

• Question 47:

  SIMULATION

  A Kubernetes worker node, named wk8s-node-0 is in state NotReady. Investigate why this is the case, and perform any appropriate steps to bring the node to a Ready state, ensuring that any changes are made permanent.

  

  You can ssh to the failed node using:

  [student@node-1] $ | ssh Wk8s-node-0

  You can assume elevated privileges on the node with the following command:

  [student@w8ks-node-0] $ | sudo -i

  Correct Answer: Check the answer in explanation.

  

  

  

• Question 48:

  SIMULATION

  Check to see how many worker nodes are ready (not including nodes tainted NoSchedule) and write the number to /opt/KUCC00104/kucc00104.txt.

  Correct Answer: Check the answer in explanation.

  

  

• Question 49:

  SIMULATION

  From the pod label name=cpu-utilizer, find pods running high CPU workloads and write the name of the pod consuming most CPU to the file /opt/KUTR00102/KUTR00102.txt (which already exists).

  Correct Answer: Check the answer in explanation.

  

  

• Question 50:

  SIMULATION

  Create a deployment as follows:

  Name: nginx-random

  Exposed via a service nginx-random

  Ensure that the serviceand; pod are accessible via their respective DNS records

  The container(s) within any pod(s) running as a part of this deployment should use the nginx Image Next, use the utility nslookup to look up the DNS records of the service and pod and write the output to /opt/KUNW00601/service.dns and /opt/

  KUNW00601/pod.dns respectively.

  Correct Answer: Check the answer in explanation.

  Solution: