Which protocol provides confidentiality and reliability during client-server communication?

Transport Layer Security (TLS) is the correct answer because it is specifically designed to provide both confidentiality and reliability during client-server communication. TLS achieves confidentiality through encryption, ensuring that data transmitted between the client and server cannot be read by third parties. It also enhances reliability by incorporating mechanisms for data integrity and authentication, which help ensure that the data sent is received undistorted and from a legitimate source.

While Secure Socket Layer (SSL) also offers similar functionalities, it is important to note that TLS is the successor to SSL and includes improvements in security and efficiency. HTTP, on the other hand, does not provide built-in encryption or reliable communication, typically operating in plain text without security features. File Transfer Protocol (FTP) is also not secure and does not inherently include confidentiality or reliability measures, making it unsuitable for secure client-server communication.

Thus, TLS stands out as the protocol specifically tailored for secure and reliable communications between clients and servers.