What is the concept of defensible architecture and its significance for Annex B?

• A. Optimizing performance at the expense of security.
• B. Designing systems to withstand attacks with secure defaults, validated components, and robust monitoring.
• C. Using a single vendor for all components.
• D. Preventing any changes to system architecture.

Answer: (B)

Defensible architecture means building systems that can resist and withstand attacks by starting with secure defaults, using trusted and validated components, and maintaining strong monitoring to detect and respond to incidents. This approach reduces both the likelihood and impact of breaches, supports rapid containment, and makes security properties easier to verify during assessments.

In Annex B contexts, this mindset matters because it emphasizes resilience, defense in depth, and the ability to operate safely even when parts of the environment are attacked or compromised. Secure defaults keep configurations safe out of the box, validated components reduce supply-chain and compatibility risks, and robust monitoring provides early detection, timely response, and forensics data—all aligning with the rigorous requirements typically evaluated in Annex B.

The option describing these elements—secure defaults, validated components, and robust monitoring—best captures what defensible architecture entails. Other choices either place performance ahead of security, rely on a single vendor and reduce diversity, or lock down the architecture so tightly that changes and improvements become impractical.