How does communication happen inside an EKS cluster?
Quick Answer
Pods get IPs from the CNI plugin (on EKS, the VPC CNI assigns real VPC IPs to pods); Services (ClusterIP/NodePort/LoadBalancer) provide stable virtual endpoints; CoreDNS resolves Service names to those IPs; and VPC routing/Security Groups carry the traffic between nodes.
Detailed Answer
A request to a Service DNS name (svc.namespace.svc.cluster.local) is resolved by CoreDNS to the ClusterIP, which kube-proxy (iptables/IPVS) load-balances to a Ready pod endpoint. On EKS the VPC CNI gives pods native VPC IPs so pod-to-pod traffic is plain VPC routing, and Security Groups (and optionally Security Groups for Pods) govern what is allowed.
Interview Tip
Name the pieces (VPC CNI, Service, kube-proxy, CoreDNS) and that on EKS pods get real VPC IPs — that specificity signals hands-on EKS experience.