Cluster DNS is a DNS server, in addition to the other DNS server(s) in your environment, which serves DNS records for Kubernetes services.
Namespaced addon objects are created in the namespace.
Master components provide the cluster’s control plane.
Master components make global decisions about the cluster (for example, scheduling), and detecting and responding to cluster events (starting up a new pod when a replication controller’s ‘replicas’ field is unsatisfied).
kube-proxy enables the Kubernetes service abstraction by maintaining network rules on the host and performing connection forwarding.
The container runtime is the software that is responsible for running containers.