What might limit the ability to locate 802.11 clients using WLAN infrastructure without an 802.11 tag?

The ability to locate 802.11 clients using WLAN infrastructure relies heavily on the active participation of the client devices in the network. When a client device is turned off, it effectively ceases to transmit any signals, making it impossible for the access points in the WLAN to detect or locate it. Access points use techniques like probing or association to communicate with active clients, and if a device is not powered and therefore not operational, it will not respond to any such attempts.

While the other options may present challenges under certain circumstances, they do not completely eliminate the ability to locate clients. For example, even without support for 802.11k—a protocol that aids in network management and client location—access points could still interact with clients using basic functionalities. When the radio is disabled, depending on the context, there might be some other means or states that allow for location tracking, although significantly hindered. RF channel selection primarily concerns the performance of the system and does not prevent client detection outright. Consequently, the correct choice focuses on the fundamental state of the device being off, rendering it entirely undetectable.