Certified Information Systems Security Professional (CISSP) Practice Exam

Defense in depth is a security strategy that emphasizes the importance of employing multiple layers of security controls to protect information and systems. By integrating various security measures, it creates a multi-faceted approach that is more resilient against potential threats.

The key significance of this strategy is that it recognizes that no single security measure is foolproof; vulnerabilities can exist at any point in an organization. Therefore, by layering defenses—such as physical security, firewall protection, intrusion detection systems, antivirus software, and employee training—an organization can better defend against attacks. If one layer is breached, the subsequent layers continue to offer protection, thereby enhancing the overall security posture.

This approach not only helps to mitigate risks but also addresses different methods that threat actors may use to exploit weaknesses. For example, an attacker could bypass technical controls but still get caught by another layer of defense, such as monitoring and incident response protocols.

The other options don’t capture the holistic essence of defense in depth. Simply relying on the latest technologies, concentrating on personnel training alone, or focusing solely on network security fails to incorporate the comprehensive layering needed to effectively mitigate risks in today's complex security landscape. Each layer contributes to a stronger overall defense when utilized in conjunction with other measures.