The exhibit shows the EMS Settings where various configurations related to network security are displayed. Option C is correct because, in the settings, it is indicated that HTTPS port is used (which operates over TCP) and SSL certificates are involved in securing the connection, implying the use of TLS for encryption and secure communication between FortiClient and FortiClient EMS.

Option A is incorrect because the domain that FortiClient is connecting to does not have to match the domain to which the certificate is issued. The certificate is issued by the ZTNA CA, which is a separate entity from the domain. The certificate only contains the device ID, ZTNA tags, and other information that are used to identify and authenticate the device.

Option B is incorrect because if the FortiClient EMS server certificate is invalid, FortiClient does not connect silently. Instead, it performs the Invalid Certificate Action that is configured in the settings. The Invalid Certificate Action can be set to block, warn, or allow the connection.

Option D is incorrect because default_ZTNARoot CA does not sign the FortiClient certificate for the SSL connectivity to FortiClient EMS. The FortiClient certificate is signed by the ZTNA CA, which is a different certificate authority from default_ZTNARoot CA. default_ZTNARoot CA is the EMS CA Certificate that is used to verify the identity of the EMS server.

References :=

[1]: Technical Tip: ZTNA for Corporate hosts with SAML authentication and FortiAuthenticator as IDP

[2]: Zero Trust Network Access - Fortinet