In what sublayer of the OSI model does TLS and SSL perform data encryption of network connections?

The correct answer is the application layer, where TLS (Transport Layer Security) and SSL (Secure Sockets Layer) operate to provide encryption for network connections. These protocols are utilized to secure communications over a computer network, specifically at the level where applications interact with the network.

In the context of the OSI model, the application layer is the topmost layer, responsible for interfaces and protocols for users and application processes. TLS and SSL are implemented here to ensure that data transmitted between applications remains confidential and is protected from eavesdropping or tampering during transit.

While the session layer manages sessions between applications and can also involve some interaction with protocols that handle encryption, it is not the primary layer where TLS and SSL execute their function. Similarly, the transport layer is responsible for data transmission between network devices but does not manage encryption at the application level. The data link layer pertains to node-to-node data transfer and is not involved in encryption mechanisms like TLS or SSL.

Therefore, the application layer is the most appropriate and accurate answer for the encryption of network connections using these technologies.