AWS VPC Networking Fundamentals: VPCs, Subnets, CIDR, Route Tables, IGW, and NAT Gateways

If you've provisioned a VPC from a Terraform module without fully internalising what each piece is doing, that's fine — right up until something breaks. An instance that should be reachable isn't. A private instance can't pull a package update. And you're left checking five different resources with no clear mental model of how they connect. This post builds that mental model from the ground up…