What would happen if we didn't use TCP or UDP? Switches, bridges, routers, load balancers, firewalls—these network boxes keep the internet running. Routing, blocking, mirroring, duplicating and deduplicating traffic in ways most people never think about. Without them, this document wouldn’t have reached you But the network is just one layer. The OS has its own way of handling packets—classifying, queuing, enforcing firewall rules, translating addresses, deciding what gets through and what gets d...