Which network components communicate using the RADIUS protocol for authentication and accounting?

Question

Options

• Aan access point and the endpoint device
• Ba Network Access Server and a RADIUS authentication server
• Can endpoint device and a RADIUS authentication server
• Da Network Access Server and an endpoint device

• B
  94% (48)
• C
  4% (2)
• D
  2% (1)

Explanation

RADIUS (Remote Authentication Dial-In User Service) operates between a Network Access Server (NAS) - such as a VPN concentrator, switch, or wireless controller - and a RADIUS authentication server, making B correct. The NAS acts as the intermediary: it receives connection requests from endpoint devices, then forwards credentials to the RADIUS server using the RADIUS protocol for actual authentication and accounting.

Why the distractors are wrong:

• A (access point ↔ endpoint): Access points communicate with endpoints using 802.11 (Wi-Fi) protocols, not RADIUS.
• C (endpoint ↔ RADIUS server): Endpoints never speak RADIUS directly; they use protocols like EAP or PEAP, and the NAS translates on their behalf.
• D (NAS ↔ endpoint): The NAS-to-endpoint leg uses 802.1X/EAP, not RADIUS.

Memory tip: Think of RADIUS as a "back-office" protocol - it runs behind the scenes between network infrastructure (NAS) and the authentication server, never touching the end user's device directly.

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