Which is one of the critical functions that a wireless LAN controller performs?

When WAPs are introduced to the wireless LAN controller, the WLC is responsible for synchronizing the WAPs to a standardized IOS. This allows for uniform support and features of the wireless system and is dependent on the model of WAP. WLCs can allow for autonomous WAPs to coexist; however, a WLC's main purpose is to manage lightweight access points. WLCs can be configured to work with Connected Mobile Experiences (CMX) for user triangulation, but a WLC cannot provide this service by itself. A WLC will manage the frequencies and channels for wireless clients, but using a WLC will not allow you to use all the wireless frequencies and channels.