<p>i saw some statement that clusterIP can not be accessed by external machine outside the cluster.</p>

<p>but i am not sure what the cluster mean here, does it mean cluster of pods or cluster of nodes.</p>

<p>ultimate question, can clusterIP (without node port) be accessed by other nodes?</p>

<p>Thanks</p>

<p>Yes, ClusterIP services can be reached by nodes in the cluster. Part of their purpose is to load-balance across replicas for Pods (which may be in different Nodes) so that traffic isn't all going to particular Pods. See <a href="https://stackoverflow.com/questions/54150887/clarify-ingress-load-balancer">Clarify Ingress load balancer</a></p>

<p>A ClusterIP service doesn't really live on any single Node but rather on each Node. The kube-proxy on each Node ensures that the load-balancing across instances takes place by updating each Nodes iptables</p>
