Which of the following best describes the concept of “Defense in Depth”?

The concept of "Defense in Depth" refers to a layered security approach that utilizes multiple protective measures across different levels of an organization. This strategy acknowledges that no single security control is foolproof, and therefore, it combines various defenses to protect against a wide array of threats. By implementing layers of security—such as network firewalls, intrusion detection systems, antivirus software, physical security, and user training—organizations can create a more resilient security posture.

In this approach, if one layer fails, others remain in place to mitigate potential breaches or attacks. This holistic view of security recognizes the complexities of threat landscapes, where attackers may exploit weaknesses in one area. Ultimately, "Defense in Depth" aims to enhance the overall integrity and availability of data and systems, making it a foundational principle in advanced security training.

The other options do not encapsulate the comprehensive nature of this security strategy. For instance, a single layer of protection is insufficient against sophisticated threats, while focusing on encryption at the server level or physical security alone does not address the multifaceted nature of modern cybersecurity challenges.