CCNP Infrastructure Practice Question
A network engineer is troubleshooting a Cisco Wireless LAN Controller (WLC) deployment where clients cannot associate to an SSID. The SSID is configured with WPA2-Enterprise and uses a RADIUS server for authentication. The engineer verifies that the RADIUS server is reachable and the shared secret is correct. Which additional configuration on the WLC is required for clients to successfully authenticate?
⚠ Common exam trap
The trap here is focusing on RADIUS server-side configuration when the missing piece is often the 802.1X setting on the WLAN itself.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable 802.1X on the WLAN and specify the RADIUS server.
For WPA2-Enterprise authentication, the WLAN on the WLC must be configured to use 802.1X and reference the RADIUS server. Even if the RADIUS server is reachable and the shared secret is correct, the WLAN will not trigger authentication unless 802.1X is enabled and the server is specified in the WLAN's security settings.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure the WLC management interface with a static IP address.
Why it's wrong here
The WLC management interface already has an IP address if the engineer can access it and verify RADIUS reachability. A static IP is not related to client authentication. While the management interface must be reachable to the RADIUS server, that is already confirmed. This does not address the missing 802.1X configuration on the WLAN.
- ✗
Set the WLAN to use PSK instead of Enterprise.
Why it's wrong here
Setting the WLAN to use PSK would change the authentication method to a pre-shared key, which contradicts the requirement for WPA2-Enterprise with RADIUS. PSK does not use a RADIUS server and would not provide the required enterprise-level authentication. This would not solve the issue; it would alter the security model.
- ✗
Configure the WLC as a RADIUS client on the RADIUS server.
Why it's wrong here
Configuring the WLC as a RADIUS client on the RADIUS server is necessary for the RADIUS server to accept requests from the WLC, but the question states the shared secret is correct and the server is reachable, implying this is already done. The missing configuration is likely on the WLC side, not the RADIUS server.
- ✓
Enable 802.1X on the WLAN and specify the RADIUS server.
Why this is correct
For WPA2-Enterprise, the WLAN must be configured to use 802.1X authentication and point to the correct RADIUS server. If 802.1X is not enabled or the RADIUS server is not specified on the WLAN, clients cannot authenticate. This is a common oversight when configuring enterprise SSIDs on a WLC.
Quick reference
AAA Protocol Comparison
| Protocol | Port(s) | Encryption | Transport | Primary Use |
|---|---|---|---|---|
| RADIUS | 1812 / 1813 | Password only | UDP | Network access control |
| TACACS+ | 49 | Full packet | TCP | Device administration |
| Diameter | 3868 | Full session | TCP / SCTP | Carrier / mobile networks |
| 802.1X | — | EAP-based | Layer 2 | Port-based access control |
TACACS+ encrypts the entire packet; RADIUS only encrypts the password field — a key exam distinction.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.