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…

A Host-Based Intrusion Detection System (HIDS) is a single security tool that monitors activity on individual endpoints - it is one potential layer within a defense-in-depth architecture, not the multi-layer strategy itself.

Security through obscurity relies on concealing system details to prevent attacks rather than implementing substantive controls, which is the antithesis of defense in depth's explicit, layered protection philosophy.

Defense in depth applies layered, redundant security controls - such as firewalls, intrusion detection, endpoint protection, access controls, and encryption - across the network, host, application, and data layers so no single point of failure exposes critical assets. If one control is bypassed or fails, subsequent layers continue to protect the environment. This principle is foundational to frameworks such as NIST SP 800-53 and directly addresses the risk posed by both external attacks and internal vulnerabilities.

A Network-Based Intrusion Detection System (NIDS) monitors network traffic at the perimeter or segment level - it is one component that may be incorporated into a defense-in-depth strategy, not the strategy concept itself.