Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A company has deployed a WPA2-Enterprise wireless network. Users report that they cannot authenticate. The RADIUS server logs show that authentication attempts are received but no responses are sent back to the wireless controller. The wireless controller and RADIUS server are on different subnets, separated by a firewall. Which of the following is the MOST likely cause?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
The wireless clients do not support the correct EAP method.
If clients did not support the EAP method, the RADIUS server would still send a response indicating authentication failure. The log shows no response at all, indicating a connectivity issue.
B
Best answer
The firewall is blocking RADIUS traffic on UDP ports 1812 and 1813.
RADIUS uses specific UDP ports. If these are blocked, the RADIUS server cannot send back authentication responses, causing authentication to time out.
C
Distractor review
The RADIUS server is not in the same broadcast domain as the wireless controller.
RADIUS is a Layer 7 protocol that operates over IP; it does not require the server to be in the same broadcast domain. Routers can forward the traffic.
D
Distractor review
The SSID is not being broadcast.
If the SSID were not broadcast, clients would not see the network. However, they are attempting to authenticate, so visibility is not the issue.
Common exam trap
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.
Technical deep dive
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.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A network engineer needs to connect two switches located 400 meters apart. The cable run includes high electromagnetic interference from nearby machinery. The engineer decides to use fiber optic cabling. Which transceiver type and fiber combination should be used to ensure the link reaches 400 meters while remaining cost-effective?
Question 2
A network engineer is designing a new switched network and needs to ensure that broadcast traffic from one department does not reach another department's workstations. The engineer plans to use VLANs. Which of the following must be configured on the switches to isolate broadcast domains as intended?
Question 3
A security engineer is configuring a site-to-site VPN between two branch offices. The requirement is to encrypt all traffic between the two networks using IPsec. Which IPsec mode should be used to encrypt the entire IP packet including the original header?
Question 4
A network administrator is connecting two switches to increase bandwidth and provide redundancy. Which technology should be used to combine multiple physical links into a single logical link?
Question 5
A network administrator is experiencing issues where unauthorized devices are offering IP addresses to clients, causing connectivity problems. Which security feature should be enabled on switches to prevent this?
Question 6
A network administrator is troubleshooting a connectivity issue and suspects the problem is related to the physical cabling. At which layer of the OSI model should the administrator begin their investigation?
FAQ
Questions learners often ask
What does this N10-009 question test?
Authentication checks who the user is.
What is the correct answer to this question?
The correct answer is: The firewall is blocking RADIUS traffic on UDP ports 1812 and 1813. — RADIUS uses UDP ports 1812 (authentication) and 1813 (accounting). If the firewall between the wireless controller and the RADIUS server is not allowing these ports, the RADIUS server can receive the request but cannot send back the response. The firewall must permit RADIUS traffic. The issue is not related to client EAP types, SSID broadcast, or broadcast domain requirements (RADIUS works across routed networks).
What should I do if I get this N10-009 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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