Quality of Service (QoS) is essential for prioritizing cloud services like email and real-time communication. It helps in managing bandwidth allocation and ensuring that critical applications receive the necessary resources for optimal performance.
https://community.cisco.com/t5/wireless-mobility-documents/what-is-cckm-and-how-does-it-affect-fast-and-secu

For mobility tunnels to come up between WLCs, they need to be part of the same mobility group. If they are configured with different mobility groups, the mobility tunnels will not establish, preventing the WLCs from sharing client, AP, and security information.

A fully measured wireless survey requires tools that support the active functioning of the network and allow for physical access to install and measure equipment. A PoE (Power over Ethernet) battery is necessary to power the access point during the survey. The access point itself is essential for broadcasting the signal. A ladder is needed to reach high places for proper access point placement and to measure coverage areas effectively.
References: CCNP Enterprise Wireless Design ENWLSD 300-425 and Implementation ENWLSI 300-430 Official Cert Guide
https://www.cisco.com/c/en/us/td/docs/wireless/technology/mesh/81/design/guide/b_mesh_81/Site_Preparation_

To ensure the anchored traffic remains up if a single WLC in the high-availability cluster fails, the mobility MAC address for the high-availability cluster should be configured. This allows the APs to recognize the cluster as a single entity, maintaining the CAPWAP tunnel to the anchor WLC in the DMZ even if one of the WLCs in the cluster fails.