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1.1.1. Why Networks Exist

Think of a network as a postal system for data. You need addressing (IP addresses) so packets know where to go, routing (how to get there), and delivery guarantees (did it arrive?). But unlike physical mail, networks must handle millions of "letters" per second while keeping unauthorized parties from reading or rerouting them.

The Three Problems Every Network Solves:
ProblemWhat It MeansAzure Solution
AddressingUnique identity for every resourceIP addresses (private/public), DNS
RoutingPath selection from source to destinationRoute tables, BGP, VNet peering
Access ControlWho can communicate with whomNSGs, Azure Firewall, Private Link

When you encounter an exam question about network design, ask yourself: "Which of these three problems is this question really about?"

Alvin Varughese
Written byAlvin Varughese
Founder15 professional certifications