Computer Networking
Cloud & Production Networking

Cloud & Production Networking

Networking concepts as they show up in a cloud console: VPCs, subnets and routing, security groups versus network ACLs, NAT gateways for outbound-only access, and the ways cloud providers connect private networks to each other.

01The Cloud Network Model - VPC, Region, AZ, Subnet

How a cloud private network is built - VPC or VNet, region versus availability zone, where a subnet lives in AWS, GCP and Azure, reserved IPs, and how to plan CIDR blocks you will not have to redo.

02Routing in a VPC - Route Tables, IGW and NAT

How a cloud subnet decides where a packet goes - route tables, the implicit local route, longest-prefix match, IGW and NAT targets, and what actually makes a subnet public or private.

03Security Groups vs Network ACLs

How the two cloud packet filters differ - stateful allow-only security groups at the network interface versus stateless numbered NACLs at the subnet edge - and how Azure NSGs and GCP firewall rules map onto them.

04NAT Gateways and Egress - Paths, Ports and the Bill

How private cloud subnets reach the internet - managed NAT in AWS, GCP and Azure, IGW versus NAT versus egress-only IGW, SNAT port limits, and why NAT is a top line on the cloud bill and how gateway endpoints cut it.

05Private Connectivity Between Networks

How to connect VPCs to each other and to on-premises networks - peering, Transit Gateway hubs, site-to-site VPN, and dedicated links - and how to pick, count and fail over between them.

06Reaching Cloud Services Privately - Endpoints and PrivateLink

How a private subnet reaches S3, SQS or a SaaS vendor without NAT or the internet - gateway endpoints, interface endpoints and PrivateLink, VPC DNS, split-horizon, and the GCP and Azure equivalents.

07Cloud Load Balancers and Ingress

Pick between the cloud load balancer families (AWS ALB, NLB, GWLB and their GCP and Azure counterparts), and reason about health checks, cross-zone behaviour, client IP, idle timeouts and the 502, 503 and 504 errors they produce.

08Kubernetes Networking - Pods, Services, kube-proxy, CNI, Ingress

How Kubernetes wires networks - one IP per pod, Service virtual IPs turned into pod IPs by kube-proxy DNAT, CNI plugin families, Ingress and Gateway API, CoreDNS and the ndots:5 trap, and NetworkPolicy.

09Debugging Cloud Networks - Flow Logs, Reachability, Mirroring

Debug a cloud network you cannot SSH into - read VPC flow logs (ACCEPT vs REJECT), prove a path with Reachability Analyzer or Connectivity Tests, and capture real packets with traffic mirroring.

10Design a VPC - The Interview Exercise

Walk the classic interview prompt, design a VPC for a 3-tier app across 3 AZs, end to end - requirements, CIDR plan, routing, security, ingress, egress, endpoints, hybrid, failure modes and cost - with a scoring rubric and follow-up drills.

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