The result of using this authentication protocol in the configuration is that the authentication and authorization requests are grouped in a single packet. This is because the configuration uses RADIUS as the AAA protocol, which combines both authentication and authorization functions in one process. RADIUS is facilitated through AAA and can be enabled only through AAA commands. The aaa new-model global configuration command enables AAA, and the radius-server host command specifies the IP address and the shared secret key of the RADIUS server. The aaa authentication command defines the method list for RADIUS authentication, and the aaa group server command defines the group name and the members of the group. The line and interface commands enable the defined method list to be used. When a user tries to access the router, the router sends a single Access-Request packet to the RADIUS server, which contains the user credentials and other attributes. The RADIUS server then verifies the credentials and returns either an Access-Accept packet, which grants access and may include authorization information, or an Access-Reject packet, which denies access. Therefore, the correct answer is D. References:
* Security Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst ...
* Configuring Basic AAA on an Access Server - Cisco
* AAA Server Priority explained with New Radius Server Command Line
* Configuring AAA on Cisco Devices - RADIUS and TACACS+ - Study-CCNA