In security architecture, what does the principle of defense in depth entail?

The principle of defense in depth emphasizes the use of multiple layers of security controls throughout an organization's IT environment. This approach recognizes that no single security measure is foolproof, and a combination of defensive strategies can more effectively protect against a variety of threats.

By implementing layers of security—such as firewalls, intrusion detection systems, antivirus programs, encryption, and user access controls—organizations create a more resilient security posture. If one layer is breached, additional layers remain in place to prevent or mitigate further unauthorized access or attacks. This layered approach leads to a more comprehensive security strategy that addresses vulnerabilities from different angles and accounts for the possibility of human error or system failure.

In contrast, relying on a single layer of security, focusing solely on physical security, or implementing redundancy in network devices does not provide the robust protection offered by a well-planned defense in depth strategy. Each of these alternative options lacks the thoroughness and adaptability needed to combat evolving security threats effectively.