Which protocol, utilizing port 3389, enables users to share desktop remotely?

The protocol that enables users to share a desktop remotely and utilizes port 3389 is Remote Desktop Protocol (RDP). RDP is a proprietary protocol developed by Microsoft that allows users to connect to another computer over a network connection. It is primarily used for remote administration of servers and desktops, providing a graphical interface for users to interact with the remote system as if they were physically present.

RDP supports multiple session management features, including clipboard sharing, disk redirection, and printer redirection, which enhances the remote desktop experience. Its use of port 3389 is well-known, making it easy to configure devices and network firewalls to allow or restrict RDP access.

In contrast, Hypertext Transfer Protocol (HTTP) facilitates the transfer of web pages but does not provide remote desktop capabilities. Simple Network Management Protocol (SNMP) is used for network management and monitoring rather than remote desktop sharing. File Transfer Protocol (FTP) is designed for transferring files between systems but lacks any functionality for desktop sharing or remote control. Thus, RDP is specifically designed for the purpose of remote desktop access, making it the correct choice.