Hey @DEREK YEO ,
To see a a list of all the cluster VM's including the master, you'll have to use the bosh cli. This guide might help:
https://docs.pivotal.io/pks/1-5/verify-health.html#k8s
In a PKS cluster, the master(s) is not listed when you run `kubectl get nodes` because it is not running the `kubelet` process.