A network engineer is establishing a wireless network for handheld inventory scanners in a manufacturing company's warehouse. The engineer needs an…

RADIUS (Remote Authentication Dial-In User Service) is the industry-standard protocol for providing centralized Authentication, Authorization, and Accounting (AAA) for network access, including 802.1X for Wi-Fi. A RADIUS server can integrate with Active Directory to validate user credentials. It can also enforce authorization policies to control which devices (the scanners) are permitted on the network, fulfilling the dual requirement of authenticating users and authorizing the specific devices they use.

A. TACACS+: This protocol is primarily designed for network device administration (e.g., authenticating administrators to routers and switches), not for authenticating end-users and devices for network access.
C. LDAP: This is a directory access protocol used to query and manage information in a directory service like Active Directory. A RADIUS server uses LDAP, but LDAP itself is not the network access authentication protocol.
D. PKI: Public Key Infrastructure is a framework for managing digital certificates. While certificates from a PKI can be used for authentication (e.g., EAP-TLS), PKI is a component of an authentication solution, not the complete AAA protocol itself.

1. Kurose, J. F., & Ross, K. W. (2021). Computer Networking: A Top-Down Approach (8th ed.). Pearson. In Chapter 8.7.2, "IEEE 802.11i," the text describes the 802.1X authentication process, explicitly naming the authentication server, which "is almost always a RADIUS server," as the entity that communicates with the access point to authenticate a user or device.

2. IETF RFC 2865, "Remote Authentication Dial In User Service (RADIUS)." Section 1.2, "Overview of Operation," details the protocol's function where a Network Access Server (NAS), such as a wireless access point, passes user authentication information to a central RADIUS server.

3. Stallings, W. (2017). Cryptography and Network Security: Principles and Practice (7th ed.). Pearson. Chapter 17, "IEEE 802.11 Wireless LAN Security," explains that the 802.1X standard uses an authentication server, typically RADIUS, to provide robust, centralized authentication for wireless clients.

4. Massachusetts Institute of Technology (MIT). (2018). 802.1x "Port-Based" Authentication. MIT Information Systems and Technology. This document outlines that 802.1X authentication relies on a RADIUS server to "validate the credentials of the connecting device" against a central directory.