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Hello, and welcome to this section on Kubernetes networking. My name is Mumshad Mannambeth. This lesson covers the core networking concepts you need to design, operate, and troubleshoot Kubernetes clusters. A solid understanding of a few foundational networking topics will help you get the most from this section. Before diving into cluster-specific details, make sure you are comfortable with:
  • Configuring network interfaces and IP addresses
  • Gateways and routing basics
  • Name resolution and DNS fundamentals
  • DNS configuration on Linux systems
  • CoreDNS basics
  • Network namespaces and how container runtimes (for example Docker) use them
These short prerequisite lectures are optional but recommended. If you already know these basics, skip what you don’t need — but review network namespaces and Docker networking if you haven’t, since they directly affect how pods and containers are isolated and connected.
A presentation slide titled "Networking" showing a vertical list of seven prerequisite topics (Switching and Routing, CoreDNS, Tools, DNS, CNI, Networking in Docker, and Networking Configuration on Cluster Nodes). A presenter stands to the right, gesturing while speaking.
Why these prerequisites matter
  • Network namespaces define per-process network stacks used by container runtimes; understanding them makes pod isolation and container networking much clearer.
  • Gateways, routes, and interface configuration are essential when diagnosing connectivity problems between nodes, pods, and external services.
  • DNS and CoreDNS are central to Kubernetes service discovery — misconfiguration here is a common source of application failures.
Learning sequence (what we’ll cover) To provide a clear learning path, this lesson follows an ordered sequence that builds from cluster-level requirements to higher-level routing and ingress patterns:
  1. Cluster networking needs — what Kubernetes expects from the network
  2. Pod networking concepts — IP addressing, isolation, and reachability for pods
  3. CNI in Kubernetes — how Container Network Interface plugins provide pod networking
  4. Service networking — ClusterIP, NodePort, and stable endpoints for applications
  5. Cluster DNS — how Kubernetes implements DNS (CoreDNS) for service discovery
  6. Network load balancers — external access patterns and load balancing options
  7. Ingress and Gateway API — HTTP routing and the newer Gateway API for advanced ingress
A presentation slide titled "Networking" shows a vertical timeline of topics (POD Networking Concepts; CNI in Kubernetes; Service Networking; Cluster DNS; Network Load Balancer; Ingress; Gateway API). On the right, a presenter in a dark sweater with red stripes gestures while speaking against a white background.
What you’ll gain from this lesson
  • A mental model of how Kubernetes connects pods, services, and external clients.
  • Practical knowledge of CNI plugins and how they affect pod IP allocation and routing.
  • Familiarity with Service types (ClusterIP, NodePort, LoadBalancer), when to use each, and common troubleshooting steps.
  • Understanding of Cluster DNS (CoreDNS) patterns for service discovery and name resolution.
  • An overview of ingress patterns, load balancers, and the Gateway API for modern HTTP routing.
Quick reference — concepts and resources
ConceptPurposeWhere to start
Pod networkingIP addressing and connectivity between containersPod CIDR, network namespaces
CNIPlugin model for providing pod network connectivityCNI plugins (Calico, Flannel, Cilium)
Service typesStable access to pods: ClusterIP, NodePort, LoadBalancerkubectl get svc and Service spec
Cluster DNSService discovery via CoreDNSCoreDNS ConfigMap and kube-dns
Ingress / Gateway APIHTTP routing and advanced ingress featuresIngress controllers; Gateway API docs
Network namespacesProcess-level networking isolationip netns, container runtime networking
Further reading and references By the end of this lesson you should be able to reason about IP addressing and routing inside a cluster, choose appropriate CNI and Service types for common application topologies, and troubleshoot common DNS and ingress-related networking issues.

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