Explanation
When you use the sync yes option in the event cli command, the EEM applet runs before the CLI command is executed. The EEM applet should set the _exit_status variable to indicate whether the CLI command should be executed (_exit_status set to one) or not (_exit_status set to zero).
With the sync no option, the EEM applet is executed in background in parallel with the CLI command.

Explanation
802.1Q VLAN identifier space is only 12 bits. The VXLAN identifier space is 24 bits. This doubling in size allows the VXLAN ID space to support 16 million Layer 2 segments -> Answer 'VXLAN extends the Layer 2 Segment ID field to 24-bits, which allows up to 4094 unique Layer 2 segments over the same network' is not correct.
VXLAN is a MAC-in-UDP encapsulation method that is used in order to extend a Layer 2 or Layer 3 overlay network over a Layer 3 infrastructure that already exists.

FlexConnect is a wireless solution for branch office and remote office deployments. It enables customers to configure and control access points in a branch or remote office from the corporate office through a wide area network (WAN) link without deploying a controller in each office.
The FlexConnect access points can switch client data traffic locally and perform client authentication locally when their connection to the controller is lost. When they are connected to the controller, they can also send traffic back to the controller. In the connected mode, the FlexConnect access point can also perform local authentication.

Explanation

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.
Reference: CCNP and CCIE Enterprise Core ENCOR 350-401 Official Cert Guide