What network security concept requires multiple layers of security controls to be placed throughout an IT infrastructure, which improves the security posture of an organization to defend against…

Security through obscurity relies on hiding implementation details to provide security rather than implementing multiple independent protective control layers.

A Host-Based Intrusion Detection System monitors a single host for malicious activity - it is one security component, not a multi-layer defense strategy.

Defense in depth applies multiple overlapping security controls at network, host, application, and physical layers, derived from the military principle of using redundant defensive positions. If one control fails or is bypassed, additional layers still provide protection and limit the blast radius of an attack. This approach significantly reduces the overall attack surface and is a foundational principle in frameworks such as NIST SP 800-53.

A Network-Based Intrusion Detection System monitors network traffic for intrusions and is also a single-layer control, not a comprehensive multi-layered defense strategy.