According to the exhibit, the User-Name attribute in the RADIUS Access-Request packet contains the client MAC address of 00:0c:29:6a:2b:3d. This indicates that FortiSwitch is authenticating the client using MAC authentication bypass (MAB), which is a method of authenticating devices that do not support 802.1X by using their MAC address as the username and password.

According to the exhibit, the wireless guest users are getting a certificate error while loading the captive portal login page. This means that the browser cannot verify the identity of the server that is hosting the login page.
Therefore, option A is true because the external server FQDN is incorrect, which means that it does not match the common name or subject alternative name of the server certificate. Option B is also true because the wireless user's browser is missing a CA certificate, which means that it does not have the root or intermediate certificate that issued the server certificate. Option C is false because the FortiGate authentication interface address is using HTTPS, which is a secure protocol that encrypts the communication between the browser and the server. Option D is false because the user address is not in DDNS form, which is not related to the certificate error.

Explanation
According to the FortiGate Administration Guide, "EAP-TLS is the most secure EAP method. It requires a digital certificate on both the server end and the client end. The server and client authenticate each other using their certificates." Therefore, option D is true because it describes the EAP method that requires the use of a digital certificate on both the server end and the client end. Option A is false because EAP-TTLS only requires a digital certificate on the server end, not the client end. Option B is false because PEAP also only requires a digital certificate on the server end, not the client end. Option C is false because EAP-GTC does not require a digital certificate on either the server end or the client end.

According to the exhibit, the network topology and SSID settings show that FortiGate is configured to use an external captive portal hosted on FortiAuthenticator, which is connected to a Windows AD server for user authentication. However, wireless users are not able to see the captive portal login page, which means that they are not redirected to the external captive portal URL. Therefore, option B is true because adding the FortiAuthenticator and WindowsAD address objects as exempt destinations services will allow the wireless users to access the external captive portal URL without being blocked by the firewall policy. Option A is false because enabling NAT in the firewall policy with the ID 13 will not affect the redirection to the external captive portal URL, but rather the source IP address of the wireless traffic. Option C is false because enabling the captive-portal-exempt option in the firewall policy with the ID 12 will bypass the captive portal authentication for the wireless users, which is not the desired outcome. Option D is false because removing the guest.portal user group in the firewall policy with the ID 12 will prevent the wireless users from being authenticated by FortiGate, which is required for accessing the external captive portal.

Windows Active Directory domain authentication enables FortiAuthenticator to join a Windows Active Directory domain as a machine entity and proxy authentication requests using Kerberos.