Which protocol uses ports TCP 20 and TCP 21?

The correct answer is FTP, which stands for File Transfer Protocol. FTP is an established method used for transferring files over a network and typically uses two different TCP ports: TCP 20 and TCP 21.

TCP 21 is the control port used for sending commands and receiving responses between the client and server, while TCP 20 is utilized for the data transfer. This separation of control and data channels is a characteristic feature of the FTP protocol, allowing for efficient file management and transfer operations.

Understanding the function of these ports within FTP is crucial for networking and security. In contrast, other protocols listed, such as FTPS, SSH, and SFTP, utilize different ports and may have varying underlying mechanisms for secure file transfer or remote access, distinguishing them further from traditional FTP. This knowledge is essential for recognizing how various protocols operate and securing enterprise networks effectively.