Download Implementing and Operating Cisco Enterprise Network Core Technologies (ENCOR).PassLeader.350-401.2021-03-18.1e.280q.vcex

Mobility Express is the ability to use an access point (AP) as a controller instead of a real WLAN controller. But this solution is only suitable for small to midsize, or multi-site branch locations where you might not want to invest in a dedicated WLC. A Mobility Express WLC can support up to 100 APs. Mobility Express WLC also uses CAPWAP to communicate to other APs.  
Note: Local mode is the most common mode that an AP operates in. This is also the default mode. In local mode, the LAP maintains a CAPWAP (or LWAPP) tunnel to its associated controller.

Agentless tool means that no software or agent needs to be installed on the client machines that are to be managed. Ansible is such an agentless tool. In contrast to agentless tool, agent-based tool requires software or agent to be installed on the client. Therefore the master and slave nodes can communicate directly without the need of high-level language interpreter.  

The tunneling technology used for the fabric data plane is based on Virtual Extensible LAN (VXLAN). VXLAN encapsulation is UDP based, meaning that it can be forwarded by any IP-based network (legacy or third party) and creates the overlay network for the SD-Access fabric.  
Although LISP is the control plane for the SD-Access fabric, it does not use LISP data encapsulation for the data plane; instead, it uses VXLAN encapsulation because it is capable of encapsulating the original Ethernet header to perform MAC-in-IP encapsulation, while LISP does not. Using VXLAN allows the SD-Access fabric to support Layer 2 and Layer 3 virtual topologies (overlays) and the ability to operate over any IP-based network with built-in network segmentation (VRF instance/VN) and built-in group-based policy.

The TCP port 6514 has been allocated as the default port for syslog over Transport Layer Security (TLS).  
Reference: https://tools.ietf.org/html/rfc5425

A Cisco lightweight wireless AP needs to be paired with a WLC to function.    
An AP must be very diligent to discover any controllers that it can join—all without any preconfiguration on your part. To accomplish this feat, several methods of discovery are used.  
The goal of discovery is just to build a list of live candidate controllers that are available, using the following methods: 
Prior knowledge of WLCs  
DHCP and DNS information to suggest some controllers (DHCP Option 43)  
Broadcast on the local subnet to solicit controllers    
Reference: CCNP and CCIE Enterprise Core ENCOR 350-401 Official Cert Guide   
If you do not tell the LAP where the controller is via DHCP option 43, DNS resolution of “Cisco-capwap-controller.local_domain”, or statically configure it, the LAP does not know where in the network to find the management interface of the controller.  
In addition to these methods, the LAP does automatically look on the local subnet for controllers with a 255.255.255.255 local broadcast.    
Reference: https://www.cisco.com/c/en/us/support/docs/wireless/5500-series-wireless-controllers/119286-lap-notjoin-wlc-tshoot.html

Proxy ingress tunnel router (PITR): A PITR is an infrastructure LISP network entity that receives packets from non-LISP sites and encapsulates the packets to LISP sites or natively forwards them to non-LISP sites.  
Reference: https://www.ciscopress.com/articles/article.asp?p=2992605

Summary ASBR LSA (Type 4) - Generated by the ABR to describe an ASBR to routers in other areas so that routers in other areas know how to get to external routes through that ASBR.

802.11r Fast Transition (FT) Roaming is an amendment to the 802.11 IEEE standards. It is a new concept for roaming. The initial handshake with the new AP occurs before client roams to the target AP. Therefor it is called Fast Transition. 802.11r provides two methods of roaming:  
Over-the-air: With this type of roaming, the client communicates directly with the target AP using IEEE 802.11 authentication with the Fast Transition (FT) authentication algorithm.  
Over-the-DS (distribution system): With this type of roaming, the client communicates with the target AP through the current AP. The communication between the client and the target AP is carried in FT action frames between the client and the current AP and is then sent through the controller.  
But both of these methods do not deal with legacy clients.   
The 802.11k allows 11k capable clients to request a neighbor report containing information about known neighbor APs that are candidates for roaming.  
 
Reference: https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/80211r-ft/b-80211r-dg.html  
IEEE 802.11v is an amendment to the IEEE 802.11 standard which describes numerous enhancements to wireless network management. One such enhancement is Network assisted Power Savings which helps clients to improve the battery life by enabling them to sleep longer.  
Another enhancement is Network assisted Roaming which enables the WLAN to send requests to associated clients, advising the clients as to better APs to associate to. This is useful for both load balancing and in directing poorly connected clients.
  
Reference: https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/config-guide/b_wl_16_10_cg/802-11v.pdf 
Cisco 802.11r supports three modes: 
Pure mode: only allows 802.11r client to connect 
Mixed mode: allows both clients that do and do not support FT to connect 
Adaptive mode: does not advertise the FT AKM at all, but will use FT when supported clients connect    
Therefore “Adaptive mode” is the best answer here.