IMPORTANT KUBERNETES COMMAND:

Regenerate Join command from master Node:

$kubeadm token create — print-join-command

# Open Multiple firewall port.

# Enable multiple firewall port using single command
firewall-cmd --zone=public --permanent --add-port={6443,2379,2380,10250,10251,10252}/tcp
#In case anything goes wrong, you can always repeat the process.
Run this on Master and Workers: 
$kubeadm reset && rm -rf /etc/cni/net.d
# Uninstall Node from Master Node 
$kubectl delete node <Name of Node>
# To evict the pods from the node for maintenance/activity. It will recreate pods in other nodes (if Replicaset). For single pod use option (--force)
$kubectl drain <Node Name> --ignore-daemonsets 
#Mark node03 as unschedulable but do not remove any apps currently running on it .
$kubectl cordon node03
# Delete the pods forcefully.
$kubectl delete pod --grace-period=0 --force --namespace
# How many Kube-proxy pod deployed in cluster.
$ kubectl get pods -n kube-system
# Get IP range configured for Services within cluster.
$ cat /etc/kubernetes/manifests/kube-apiserver.yaml | grep cluster-ip-range
#What type of proxy is the kube-proxy configured to use?
- Check the logs of the kube-proxy pods. 
$kubectl logs kube-proxy-ft6n7 -n kube-system
# Sort persistent volume based on their capacity.
$kubectl get pv --sort-by=.spec.capacity.storage
NAME       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   REASON   AGE
pv-log-4   40Mi       RWX            Retain           Available                                   21m
pv-log-1   100Mi      RWX            Retain           Available                                   21m
pv-log-2   200Mi      RWX            Retain           Available                                   21m
pv-log-3   300Mi      RWX            Retain           Available                                   21m
# Retrieve just the first 2 columns of output and store it in the columns should be named NAME and CAPACITY.
$kubectl get pv --sort-by=.spec.capacity.storage -o=custom-columns=NAME:.metadata.name,CAPACITY:.spec.capacity.storage
NAME       CAPACITY
pv-log-4   40Mi
pv-log-1   100Mi
pv-log-2   200Mi
pv-log-3   300Mi