An external attacker has compromised an organization's network security perimeter and installed a sniffer onto an inside computer. Which of the following is the MOST effective layer of security the or

Packet filtering on perimeter firewalls controls ingress and egress traffic at the network boundary but does not restrict what an internal sniffer can observe on the local network segment after the perimeter has already been breached.

HIDS monitors activity on individual hosts and can detect suspicious behavior, but it does not prevent a sniffer already installed on a different compromised host from capturing network traffic traversing shared segments.

Strong authentication for administrators protects privileged account access but does not limit the network traffic visible to a sniffer that has already been installed on an internal machine by an attacker who bypassed the perimeter.

Logical network segmentation using VLANs and switch-level controls confines broadcast traffic to specific segments, meaning a sniffer on one compromised host can only capture traffic within its own VLAN or subnet. This directly limits lateral reconnaissance by preventing the attacker from seeing traffic destined for other segments. Without segmentation, a sniffer on a flat network can potentially capture all broadcast and multicast traffic across the entire organization.