Question

A developer writes an application that stores a list of peer Pod IP addresses in a config file when it starts, so it can talk directly to those specific Pods. After a few days, the application frequently fails to reach its peers even though all Pods appear healthy. What is the fundamental Kubernetes concept the developer has overlooked?

Accepted Answer

Pods are ephemeral and receive a new IP address each time they are recreated, so hardcoding Pod IPs is unreliable.

Answer

Pod IP addresses are only reachable from within the same node, so cross-node communication requires NodePort.

Answer

Kubernetes assigns each Pod a permanent IP, but the kube-proxy periodically rotates them for security.

Answer

Pods cannot communicate by IP at all; all inter-Pod traffic must go through a Service ClusterIP.