- A
The guest SSID is configured with open authentication, which does not support captive portal.
Why wrong: Incorrect because open authentication is commonly used with captive portals; the portal handles authentication after association.
- B
The redirect ACL is missing entries for DNS and HTTP traffic to the captive portal server.
Correct because the redirect ACL must permit DNS and HTTP traffic to the portal server so that the client's initial HTTP request is redirected to the captive portal.
- C
The WLC does not have a dedicated guest interface configured.
Why wrong: Incorrect because a dedicated guest interface is not mandatory; the WLC can use a VLAN interface for guest traffic.
- D
The captive portal requires a RADIUS server to be configured on the WLC.
Why wrong: Incorrect because captive portal can use local authentication or an external web server; RADIUS is optional.
Quick Answer
The answer is that the redirect ACL is missing entries for DNS and HTTP traffic to the captive portal server. On a Cisco 9800 WLC, the redirect ACL defines which client traffic is intercepted and redirected to the captive portal; without explicit permit statements for DNS resolution and HTTP access to the portal server’s IP address, the client’s initial web request is never forwarded to the portal, leaving the user stuck with an association but no redirect. This scenario tests your understanding of how guest captive portal redirect ACL configuration works in the ENCOR 350-401 exam, where a common trap is assuming any HTTP traffic is automatically redirected—instead, the ACL must explicitly match the traffic destined for the portal. A reliable memory tip is “DNS and HTTP to the portal must be permitted in the ACL; everything else is redirected.”
CCNP Wireless Infrastructure Practice Question
This 350-401 practice question tests your understanding of wireless infrastructure. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An engineer is configuring a new Cisco 9800 WLC in a branch office. The WLC will manage 50 APs and must provide guest access with a captive portal. The engineer configures a guest SSID with open authentication and a redirect ACL for the captive portal. However, after the configuration, clients can associate to the guest SSID but cannot reach the captive portal page. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
The redirect ACL is missing entries for DNS and HTTP traffic to the captive portal server.
The correct answer is that the redirect ACL is not properly configured to allow DNS and HTTP traffic to the captive portal server. Without proper ACL entries, the client's HTTP request is not redirected to the portal. The other options are incorrect because open authentication does not require a pre-shared key, the WLC does not need a specific interface for guest traffic (it can use a service port or management interface), and captive portal does not require RADIUS authentication by default.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The guest SSID is configured with open authentication, which does not support captive portal.
Why it's wrong here
Incorrect because open authentication is commonly used with captive portals; the portal handles authentication after association.
- ✓
The redirect ACL is missing entries for DNS and HTTP traffic to the captive portal server.
Why this is correct
Correct because the redirect ACL must permit DNS and HTTP traffic to the portal server so that the client's initial HTTP request is redirected to the captive portal.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Authentication checks who the user is.
- ✗
The WLC does not have a dedicated guest interface configured.
Why it's wrong here
Incorrect because a dedicated guest interface is not mandatory; the WLC can use a VLAN interface for guest traffic.
- ✗
The captive portal requires a RADIUS server to be configured on the WLC.
Why it's wrong here
Incorrect because captive portal can use local authentication or an external web server; RADIUS is optional.
Common exam traps
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
- Authentication checks who the user is.
- Authorization controls what the user is allowed to do after login.
- Privilege levels affect access to EXEC and configuration commands.
- AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
- Do not assume successful login means full administrative access.
- Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
- Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
How this comes up in practice
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
Got this wrong? Here's your next step.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 350-401 questions on access control and AAA configuration.
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FAQ
Questions learners often ask
What does this 350-401 question test?
Wireless Infrastructure — This question tests Wireless Infrastructure — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: The redirect ACL is missing entries for DNS and HTTP traffic to the captive portal server. — The correct answer is that the redirect ACL is not properly configured to allow DNS and HTTP traffic to the captive portal server. Without proper ACL entries, the client's HTTP request is not redirected to the portal. The other options are incorrect because open authentication does not require a pre-shared key, the WLC does not need a specific interface for guest traffic (it can use a service port or management interface), and captive portal does not require RADIUS authentication by default.
What should I do if I get this 350-401 question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 350-401 questions on access control and AAA configuration.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Authentication checks who the user is.
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Last reviewed: Jun 18, 2026
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