Exam GICSP Topic 1 Question 8 Discussion

The diagram shows multiple subnets/zones (Levels 0-3) connected via routers and switches. To enforce traffic flow policies between these zones/subnets, the router should implement Access Control Lists (ACLs) (B).
ACLs can:
Filter traffic between subnets based on IP addresses, ports, and protocols Enforce security boundaries as per ICS segmentation principles (A) MAC-based port security controls device-level access but is less effective for inter-subnet traffic control.
(C) Secure Shell (SSH) is for secure device management, not traffic control.
(D) 802.1x provides port-based network access control but is less relevant for routing traffic between subnets.
GICSP highlights ACLs as fundamental tools for network segmentation enforcement in ICS.
Reference:
GICSP Official Study Guide, Domain: ICS Security Architecture & Design
NIST SP 800-82 Rev 2, Section 5.5 (Network Segmentation and Filtering)
GICSP Training on Network Security Controls