A customer calls the help desk to report that resources are no longer reachable.

The correct answer is Switch because the question references a new logical layout segmenting the network using tagging, which indicates VLAN (Virtual Local Area Network) configuration. VLAN tagging (IEEE 802.1Q) is performed on switches to logically separate broadcast domains within the same physical infrastructure.

According to CompTIA Network+ (N10-009) objectives under switching technologies, VLANs are used to improve security, reduce broadcast traffic, and logically segment network traffic. When VLAN tagging is misconfigured—such as incorrect trunk ports, access port assignments, or mismatched VLAN IDs—devices may lose connectivity to required network resources.

Since the issue began after changes involving tagging, the most likely cause is an incorrect switch configuration, such as improper VLAN assignments or trunking settings.

An access point (Option A) may use VLANs for SSID segmentation, but core tagging configuration is handled at the switch. A firewall (Option B) filters traffic but does not control VLAN tagging at Layer 2 in typical deployments. A load balancer (Option D) distributes traffic among servers and is unrelated to VLAN segmentation.

Therefore, reviewing the switch configuration is the appropriate action to restore connectivity.