Layered security—known as defense in depth—is a core concept in cybersecurity architecture. This episode focuses on how firewalls and demilitarized zones (DMZs) serve as essential layers in protecting internal networks. We explore different types of firewalls (packet filtering, stateful, next-gen), the design of DMZs for public-facing services, and how to enforce traffic controls between zones. You'll also learn how to implement rule sets, audit firewall logs, and support intrusion detection systems. This is critical knowledge for securing enterprise perimeters and enforcing trust boundaries.