220-1102 Question 545
Single answerWireless specificA company uses a wireless network with WPA2-Enterprise and a RADIUS server. A user reports that their company-issued laptop can see the SSID and prompts for credentials, but after entering valid domain credentials, the laptop fails to connect. Other employees can connect successfully in the same area. You verify the laptop's wireless adapter is enabled and functioning, and the user can connect to an open guest Wi-Fi network. Which of the following is the MOST likely cause of the problem?
- A
The laptop is missing or has an invalid client certificate required for 802.1X authentication
- B
The wireless access point is broadcasting on too high of a channel number for the laptop to detect
- C
The SSID is hidden, so the laptop cannot complete the association process
- D
The wireless adapter does not support 5 GHz frequencies
Show answer and explanation
Correct answer: A
Explanation
This question tests practical troubleshooting of enterprise wireless authentication. In WPA2-Enterprise deployments, successful connection depends not only on radio connectivity and correct credentials but also on proper 802.1X configuration. A device that can detect the SSID, prompt for credentials, and connect to an open guest network has already ruled out many basic wireless problems such as disabled Wi-Fi, weak signal, or unsupported standards. Because other employees can connect in the same area, the access point and RADIUS infrastructure are likely operational. That makes an endpoint-specific authentication issue the most probable cause. A missing or invalid client certificate is a common real-world issue in managed enterprise environments. This aligns with standard wireless best practices and enterprise authentication models documented by vendors and administrators implementing WPA2-Enterprise with 802.1X and RADIUS.
- A. Correct.
Correct. In a WPA2-Enterprise environment, authentication commonly uses 802.1X with a RADIUS server and may require a valid client certificate depending on the EAP method in use, such as EAP-TLS or PEAP configurations with machine/user certificate requirements. If the laptop can see the SSID and connect to an open guest network, the wireless radio is working. If other users can connect to the corporate SSID, the infrastructure is likely functioning. A missing, expired, or invalid client certificate is a realistic endpoint-specific cause of authentication failure after credentials are entered.
- B. Incorrect.
Incorrect. If the laptop can see the SSID, the channel is already being detected by the device. Also, channel numbering itself is not the issue described here. The system is able to discover the network and begin authentication, so the failure is occurring later in the process.
- C. Incorrect.
Incorrect. A hidden SSID would affect discovery and connection setup, but the scenario states the laptop can see the SSID and is prompted for credentials. That means association has progressed far enough that a hidden SSID is not the likely cause.
- D. Incorrect.
Incorrect. If the adapter did not support 5 GHz, the laptop typically would not detect a 5 GHz-only SSID at all. The scenario explicitly says the laptop can see the corporate SSID and attempts authentication. In addition, the ability to connect to guest Wi-Fi shows the adapter works, but the issue is specific to enterprise authentication rather than radio band support.