Kubernetes Networking & Services
5 Topics
1
Kubernetes Networking Model — The Flat Network
Direct pod-to-pod communication rules.
Understand the fundamental K8s networking requirements. Interviewers will ask you to explain the 'IP-per-Pod' model and verify your knowledge of Pod-to-Pod communication requirements: every Pod gets a unique IP, and any Pod can communicate with any other Pod without NAT, regardless of which node they run on.
2
Services — ClusterIP, NodePort, LoadBalancer
Exposing pod workloads internally and externally.
Be ready to write a Service manifest and explain the different Service types: ClusterIP (internal), NodePort (opens a port on every node), and LoadBalancer (provisions a cloud LB). Understand EndpointSlices and how kube-proxy maintains forwarding rules.
3
Ingress — HTTP Routing and TLS Termination
Routing external HTTP paths to services and securing certificates.
Ingress is a production routing standard. Focus on explaining the difference between an Ingress Resource (declaration) and an Ingress Controller (the actual proxy, like Nginx, Traefik, or Envoy). Understand TLS termination rules and cert-manager setups.
4
Network Policies — Firewalling Traffic Between Pods
Declaring ingress/egress firewall rules for namespace pods.
Zero-trust networking is heavily tested. Explain the default-allow behavior of Kubernetes networks (any Pod can talk to any Pod) and how NetworkPolicies implement zero-trust firewall rules. Be ready to explain that NetworkPolicies require a CNI plugin that supports enforcement (like Calico or Cilium).
5
Service Mesh — Istio and Linkerd Overview
Sidecar patterns, mutual TLS, traffic shaping, and telemetry.
Expect questions on microservice operations. You should know what a Service Mesh solves (mTLS, canary releases, distributed tracing, circuit breakers) without modifying application code, and how the control plane (Istiod) manages Envoy sidecar proxies.