Networking issue in initial cluster setup with no network connectivity

[devleejb]

After setting up the initial cluster, it is discovered that there is no network connectivity. Attempted to troubleshoot the issue by running the following commands:

kubectl apply -f https://k8s.io/examples/admin/dns/dnsutils.yaml
kubectl exec -it dnsutils -- nslookup kubernetes.default

The expected response is not observed, and the following message is received:

;; connection timed out; no servers could be reached

Upon inspecting the /etc/resolv.conf file in the Pod, it is noted that the nameserver correctly contains the address of the kube-dns service.

What could be the underlying cause of the network issue? Need to clarify whether this setup is intentional in the cluster environment.

Reference: Kubernetes DNS Debugging and Resolution