CISSP Official Study Guide pg 73 - Defense in depth includes administrative, technical (logical) and physical controls. What's listed is only physical controls. Answer is D.

MFA + physical layer. (defense in depth)

The term "security perimeter" typically refers to the boundary or boundary defenses of a network or physical area that separates it from external threats. - In question it only focus on specific physical area. So its not D The term "defense-in-depth" refers to a security strategy that employs multiple layers of security controls and mechanisms to protect systems, networks, and data from various threats. - In question it only focus on specific physical area. So its not C also. Hence It is A

Answer C) Defense-in-Depth is an approach Keyword in question is "approach" and also remember that cameras do not prevent access, they only deter it. Security Perimeter definition: A security perimeter is all of the physical and technological barriers put in place to prevent unauthorized entry into a facility. https://solink.com/resources/glossary/security-perimeter/

Only physical assest. IT'S D

D. BEST describes this security approach as a physical security perimeter. It doesn't fulfill the Defense in depth requirement because it only covers the physical layer.

A. Access control: This refers specifically to mechanisms that manage who or what is allowed to access resources, which would include card and PIN systems but not necessarily the broader range of physical security measures mentioned. B. Security information and event management (SIEM): This involves the collection, analysis, and reporting of security data from various sources, primarily focused on digital events rather than physical security measures. C. Defense-in-depth: This is a comprehensive strategy that integrates multiple layers of security, including both physical and logical controls. The description given fits this approach as it includes multiple layers of physical security measures. D. Security perimeter: This generally refers to the boundary that separates a secured area from a non-secured area. While it can include some of the elements mentioned, it does not fully encapsulate the range of security measures described.

Def in depth. physical barrier and knowing a PIN number is already different controls.

C. Defense-in-depth The existence of physical barriers, card and personal identification number (PIN) access systems, cameras, alarms, and security guards best describes a defense-in-depth security approach. Defense-in-depth is a layered security strategy that employs multiple, overlapping security measures to protect assets. This approach ensures that if one security measure fails, others are in place to provide continued protection. By implementing a variety of security controls across different layers (physical, technical, and administrative), organizations can better safeguard their resources against various threats.

I was tempted to go with A, but after reading the CBK Reference book, I concluded the answer is D. The key phrase is "security approach." While all those mentioned are access control methods, when applied together, it is a defense-in-depth security approach.

Don't overthink it

I agree with C:, however, Microsoft Co-Pilot states it's D.

From OSG (pg. 1006). The existence of zero-day vulnerabilities makes it critical that you have a defense-in-depth approach to cybersecurity that incorporates a varied set of --'overlapping security controls'.

A. Access control. Explanation: Access control refers to the measures put in place to regulate and monitor who can access specific resources or areas within a facility or system. This includes physical access control mechanisms such as physical barriers, card access systems, PIN access systems, cameras, alarms, and security guards.

The term "security perimeter" typically refers to the boundary or boundary defenses of a network or physical area that separates it from external threats. - In quetion it only focus on specific physical area. So its not D The term "defense-in-depth" refers to a security strategy that employs multiple layers of security controls and mechanisms to protect systems, networks, and data from various threats. - In quetion it only focus on specific physical area. So its not C also. Hence It is A

How can security camera and alarm be a perimeter security?

According to CISSP "The security perimeter of your system is an imaginary boundary that separates the TCB from the rest of the system" or "Any connection to your computer system is only a communication path to a system interface; They are not labeled as a security perimeter." That is, it is not necessarily related to physical controls. Also the key word is "security approach", therefore "Defense in depth" is the answer.