Which of the following ports is designated for FTP data transfer?

The designated port for FTP data transfer is port 20. FTP, or File Transfer Protocol, operates using two separate channels for communication. While port 21 is utilized for the control connection (where commands and responses are exchanged), port 20 serves as the data connection port. This distinction allows FTP to manage the file transfer process effectively, separating the command and data transfer to ensure smoother operations.

In terms of protocol functions, when a file is actually transferred between the client and the server, port 20 is the one that facilitates the flow of this data. This is essential for maintaining the integrity and performance of the file transfers, thereby optimizing the overall FTP functionality.