Any good documents or videos which can detail the below topic?
“Execute the command ‘nslookup <any external site>’ from the pod and explain how the DNS works from within the pod”
Did you go through all of the networking section?
Check the networking section and the following:
kubectl run test-nslookup --image=busybox:1.28 --restart=Never --rm -it -- nslookup nginx-resolver-service