The diagram illustrates a standard three-tier hierarchical network model.

1. The Access layer (bottom) is where end-user devices (workstations, APs) connect to the network.
2. The Distribution layer (middle) aggregates traffic from the access layer switches and provides routing between different subnets. The ipconfig outputs confirm this, showing multiple, separate subnets (e.g., 10.31.5.x, 10.31.6.x, 10.31.10.x), which necessitates a routing layer.
3. The Core layer (top) is the high-speed backbone that connects all distribution blocks and the egress zone for high-speed transport.
4. A NIPS (Network Intrusion Prevention System) is the correct technology for the egress zone. It is deployed in-line to actively inspect and block malicious traffic before it enters or leaves the network, complementing the firewall.

Kurose, J., & Ross, K. (2021). Computer Networking: A Top-Down Approach (8th ed.).

Reference: Chapter 6.4, "A Day in the Life of a Web Page Request." This section details the hierarchical structure of institutional networks, describing the access, distribution, and core tiers and their respective functions in routing and packet forwarding.

NIST. (2007). Guide to Intrusion Detection and Prevention Systems (IDPS). (Special Publication 800-94).

Reference: Section 6.2, "IDPS Deployment." This document describes the typical in-line deployment of a Network-Based IPS (NIPS) at the network perimeter, often placed "behind the external firewall" to "detect and stop attacks that the firewall failed to block." This matches the diagram's "Egress zone" topology.

IETF. (1996). Address Allocation for Private Internets. (RFC 1918).

Reference: Section 3, "Private Address Space." This document sanctions the use of the 10.0.0.0/8 address block for private networks, as seen in all ipconfig outputs (e.g., 10.31.5.5), confirming the devices are on an internal, segmented network.