John has subscribed to a cloud-based service to synchronize data between his smartphone, tablet, and PC. Before allowing the data to be synchronized, this service uses a process in which the cloud service and the client on the smartphone will verify the security of all devices’ security certificates.
What type of security does the cloud-base service employ?
A. Mutual authentication
B. VPN
C. IMAP
D. Tethering

Mutual authentication also known as a two-way authentication is a process whereby devices within the network authenticate each other to verify that communication is established with legitimate parties. Mutual authentication occurs when the digital certificate or public key certificate of the client is trusted by the server and vice versa.

Before John is able to synchronize data between his smartphone, tablet, and PC, the digital certificates of all the devices have to be confirmed for security purposes. The Transport Layer Security (TLS) protocol is responsible for sending the digital certificates across devices, if a certificate already exists, the certificate with the latest timestamp is used for authentication.