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Hectal
Phase 3Intermediate4 of 9 in AWS

Networking — VPC from the Ground Up

CIDR blocks, public and private subnets, route tables, NAT, endpoints, and connecting VPCs — the network every other resource sits inside.

Most 'it works locally but not on AWS' problems are networking problems: a missing route, a subnet without internet access, a security group or NACL in the way, a private resource trying to reach a public endpoint. This phase builds a production-shaped VPC piece by piece so you know exactly why each piece exists — and how to debug it when traffic doesn't flow.

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4 topics ~52 min 9 code blocks & diagrams
Start with the first topic
1
3.1

VPCs, Subnets & CIDR Planning

A VPC is your own private network inside an AWS region, defined by a CIDR range; subnets carve that range into per-AZ slices, and a subnet is 'public' or 'private' purely because of its route table — not because of any setting on the subnet itself.

13 min 1 diagram 1 code practice

2
3.2

Route Tables, Internet Gateways & NAT

Route tables decide where packets go; an internet gateway gives public subnets two-way internet access, and a NAT gateway gives private subnets outbound-only access so they can download updates without being reachable from outside.

13 min 1 diagram 1 code practice

3
3.3

NACLs & VPC Endpoints

Network ACLs are a stateless, subnet-level firewall with explicit allow and deny rules; VPC endpoints let private resources reach AWS services without traversing the internet or a NAT.

13 min 2 code practice

4
3.4

Connecting Networks & Debugging with Flow Logs

VPC peering joins two VPCs directly, Transit Gateway acts as a hub for many VPCs and on-prem links, and VPC Flow Logs record accepted and rejected traffic so you can see exactly where packets stop.

13 min 1 diagram 2 code practice