Final answer:
The default ports reserved for FTP are 20 and 21 TCP, which are used for data transfer and control respectively. Options B, C, and D are incorrect as they either suggest UDP or incorrect port numbers for FTP.
Step-by-step explanation:
The ports that are, by default, reserved for use by FTP (File Transfer Protocol) are 20 and 21 TCP. Port 20 is used for data transfer, while port 21 is used for control (i.e., commands and responses). It's important to note that FTP utilizes the TCP protocol, not UDP, for these operations, as TCP provides a reliable connection and ensures the integrity of the data being transferred. Therefore, options B, C, and D, which suggest UDP or incorrect port numbers (22 and 23), do not apply to FTP. These other ports are typically associated with other services, like SSH (Secure Shell), which uses port 22 TCP.
The default ports reserved for FTP are 20 and 21 TCP, which are used for data transfer and control respectively. Options B, C, and D are incorrect as they either suggest UDP or incorrect port numbers for FTP.
The ports reserved for use by FTP (File Transfer Protocol) by default are 20 and 21 TCP (Transmission Control Protocol).