2.1. Network Components and Their Roles

💡 First Principle: Every network device exists to solve one of three problems: connecting things (access), moving data efficiently (distribution/core), or controlling behavior (management). When you see an unfamiliar device on the exam, ask: "Is this device connecting endpoints, forwarding traffic, or managing the network?" This immediately tells you its role.

What happens when you use the wrong device: Imagine using a Layer 2 switch where you need a router. Traffic between VLANs can't pass—users in Sales can't reach the servers in the Data VLAN. Or using a router where you need a firewall—traffic flows freely, including the malware. Or skipping the wireless controller for 50 APs—you spend your life configuring each one individually. Right device for the right job matters.

Think of a network like a city's transportation system. Endpoints are the buildings where people live and work. Switches are the local streets that connect buildings in a neighborhood. Routers are the highway interchanges that connect neighborhoods to each other and to the outside world. Firewalls are the security checkpoints. Controllers are the traffic management centers that coordinate everything.