Why would you require us to install etcdctl when that is not an exam requirement and needs to make use of outside documentation not allowed in the exam? The process is time consuming and if done incorrectly means that etcd is not working on cluster1 which cascades to other errors and issues. Please make etcdctl part of the image to more accurately reflect the CKA exam.
For this question, please set the context to cluster1 by running:
kubectl config use-context cluster1
An etcd backup is already stored at the path /opt/cluster1_backup_to_restore.db on the cluster1-controlplane node. Use /root/default.etcd as the --data-dir and restore it on the cluster1-controlplane node itself.
You can ssh to the controlplane node by running ssh root@cluster1-controlplane from the student-node.