Which of the following protocols uses a program layer located between the Internet’s Hypertext Transfer Protocol (HTTP) and Transport Control Protocol (TCP) layers?

A.
TFTP

B.
HTTPS

C.
SCP

D.
SSL

Explanation:
The Secure Sockets Layer (SSL) is a commonly-used protocol for managing the security of a message transmission on the Internet. SSL has recently been succeeded by Transport Layer Security (TLS), which is based on SSL. SSL uses a program layer located between the Internet’s Hypertext Transfer Protocol (HTTP) and Transport Control Protocol (TCP) layers. SSL is included as part of both the Microsoft and Netscape browsers and most Web server products. URLs that require an SSL connection start with https: instead of http:.Answer option C is incorrect. The SCP protocol sends data in encrypted format. It is used to prevent potential packet sniffers from extracting usable information from data packets. The protocol itself does not provide authentication and security; it relies on the underlying protocol, SSH, to provide these features. SCP can interactively request any passwords or passphrases required to make a connection to a remote host, unlike rcp that fails in this situation. The SCP protocol implements file transfers only. It does so by connecting to the host using SSH and there executes an SCP server (scp). The SCP server program is typically the same program as the SCP client. Answer option A is incorrect. Trivial File Transfer Protocol (TFTP) is a file transfer protocol, with the functionality of a very basic form of File Transfer Protocol (FTP). TFTP can be implemented in a very small amount of memory. It is useful for booting computers such as routers which did not have any data storage devices. It is used to transfer small amounts of data between hosts on a network, such as IP phone firmware or operating system images when a remote X Window System terminal or any other thin client boots from a network host or server. The initial stages of some network based installation systems (such as Solaris Jumpstart, Red Hat Kickstart and Windows NT’s Remote Installation Services) use TFTP to load a basic kernel that performs the actual installation. TFTP uses UDP port 69 for communication. Answer option B is incorrect. Hypertext Transfer Protocol Secure (HTTPS) is a combination of the Hypertext Transfer Protocol with the SSL/TLS protocol to provide encryption and secure (website security testing) identification of the server. HTTPS connections are often used for payment transactions on the World Wide Web and for sensitive transactions in corporate information systems. Difference from HTTP As opposed to HTTP URLs which begin with "http://" and use port 80 by default, HTTPS URLs begin with "https://" and use port 443 by default. HTTP is insecure and is subject to man-in-the-middle and eavesdropping attacks which can let attackers gain access to website accounts and sensitive information. HTTPS is designed to withstand such attacks and is considered secure.