2.8. Modern Network Environments

💡 First Principle: Traditional networks assumed a hard perimeter—inside is trusted, outside is untrusted. Modern networks recognize that users, applications, and data have moved beyond traditional boundaries. Zero trust assumes compromise and verifies every request; SDN separates control from forwarding to enable programmability.

What breaks without modern architecture understanding? Apply perimeter thinking to cloud-first environments, and cloud resources remain unprotected because they're "outside" the firewall (which is meaningless in cloud). Trust internal traffic implicitly, and lateral movement after initial compromise becomes trivial—attackers pivot from compromised workstation to domain controller to data.

Think of the evolution: traditional networks are castles with walls (cross the drawbridge and you roam freely). Zero trust networks are secure facilities where every door requires authentication regardless of which room you came from.