Routing vs. switching, VLANs vs. subnets, NAT vs. PAT, SDN, zero trust, VXLAN, and MPLS — the paired concepts every later module in this program assumes you can already tell apart.
This is the hallmark module of the program. Enterprise networking is full of terms that get used interchangeably on the job even though they mean genuinely different things — a switch and a hub both have ports, a VLAN and a subnet both segment a network, NAT and PAT both rewrite addresses, and confusing any of these pairs under time pressure is exactly how a design or a troubleshooting session goes sideways. This module works through seventeen of those concepts in pairs and small groups, with real engineering depth: not just the definitions, but the mechanics underneath each one and why the distinction actually matters in a real design.
By the end of this module you should be able to explain, from first principles, why a router rewrites Layer 2 addresses at every hop but leaves Layer 3 addresses untouched, why east-west traffic reshaped modern data center fabric design, and why VXLAN exists even though VLANs already do segmentation — the same distinctions Module 5 (Switching), Module 6 (Routing), and Module 9 (Data Centers) build on in full implementation detail.