Which of the following statements about wireless devices is true?

Wireless networks commonly use Access Controllers (ACs) and Access Points (APs) to manage user connectivity.

Option A (Incorrect): Fat APs operate independently and do not require an AC to function. Instead, Fit APs require ACs to manage them centrally.

Option B (Correct): An AC (Access Controller) is usually deployed at the aggregation layer of a network. It provides centralized control over Fit APs, ensuring high-speed, secure, and reliable WLAN services. This is the standard design in enterprise WLAN architectures.

Option C (Incorrect): Fit APs do not handle authentication and forwarding on their own. Instead, they rely on an AC for these functions.

Option D (Incorrect): Many wireless devices (including APs and ACs) have wired interfaces for uplink connectivity to switches or other network devices.

Thus, the correct answer is B. An AC is usually deployed at the aggregation layer of a network to provide high-speed, secure, and reliable WLAN services.