Blocking Communication between Endpoint PCs

D.

In the given scenario, the organization has to improve its network security posture without additional resources to implement data isolation after a merger with another legal jurisdiction. One recommendation is to block communication between endpoint PCs.

Out of the given options, the BEST solution would be implementing network segmentation (Option D).

Network segmentation is a security technique used to separate parts of a network into smaller subnetworks, also known as segments or zones. It helps to reduce the attack surface of a network by limiting the access to resources and communication paths. By dividing a network into segments, network administrators can control network traffic, prevent unauthorized access to sensitive data, and mitigate the spread of malware and other threats.

Blocking communication between endpoint PCs is a specific use case for network segmentation. By separating endpoint PCs into different network segments, network administrators can limit communication between them, reducing the risk of lateral movement in case of a compromise. Network segmentation can also help to enforce access controls, monitor network activity, and apply security policies specific to each segment.

While the other options, such as installing HIDS (Option A), configuring a host-based firewall (Option B), or configuring EDR (Option C), are also useful security measures, they do not directly address the requirement of blocking communication between endpoint PCs. HIDS and EDR are endpoint security solutions that help to detect and respond to security incidents on individual devices, while a host-based firewall can provide additional protection for a single host.

In conclusion, implementing network segmentation is the BEST solution for the given scenario as it would allow the organization to block communication between endpoint PCs, improve its network security posture, and meet the requirement of not requiring additional resources to implement data isolation.