Explain Kubernetes networking model and how pod-to-pod communication works.

Kubernetes implements a flat networking model where every pod gets a unique IP address and can communicate with other pods without NAT.\n\nNetworking Principles:\n• Every pod has a unique cluster IP\n• Pods can communicate directly without NAT\n• Nodes can communicate with pods without NAT\n• Container Network Interface (CNI) plugins provide implementation\n\nComponents:\n• Cluster DNS: Service discovery via DNS names\n• kube-proxy: Load balancing and service routing\n• CNI Plugin: Network connectivity (Calico, Flannel, Weave)\n• Network Policies: Traffic filtering and security\n\nCommunication Flow:\n1. Pod A wants to communicate with Pod B\n2. Traffic goes through node's network interface\n3. CNI plugin routes traffic to destination node\n4. Destination node routes to target pod\n\nService Discovery:\n• DNS-based: service-name.namespace.svc.cluster.local\n• Environment variables: injected into pods\n• Service mesh: Advanced traffic management\n\nExample Network Policy:\napiVersion: networking.k8s.io/v1\nkind: NetworkPolicy\nmetadata:\n name: deny-all\nspec:\n podSelector: {}\n policyTypes:\n - Ingress\n - Egress\n\nBest Practices:\n• Implement network policies for security\n• Use service mesh for complex routing\n• Monitor network performance\n• Choose appropriate CNI plugin