ISA/IEC 62443 Cybersecurity Fundamentals Specialist — Question 31

Which of the following is a recommended default rule for IACS firewalls?

Answer options

• A. Allow all traffic by default.
• B. Allow IACS devices to access the Internet.
• C. Allow traffic directly from the IACS network to the enterprise network.
• D. Block all traffic by default.

Correct answer: D

Explanation

The correct answer is D, as blocking all traffic by default is a security best practice that minimizes exposure to threats. Options A, B, and C are risky because they allow unrestricted traffic or connections, which could lead to security vulnerabilities in the IACS environment.