FTP uses ........... number of connections for transferring files.

Question

Accepted Answer

The correct option is (3):
The File Transfer Protocol (FTP) uses two distinct TCP connections to facilitate file transfers, which is a key characteristic of its architecture. This design separates the flow of control information from the flow of data. The first connection is the **Control Connection**, which is established on the well-known TCP Port 21. This connection remains active for the duration of the FTP session and is used solely for sending commands (like username, password, or file retrieval requests) and receiving server responses. The second connection is the **Data Connection**, which is temporarily opened specifically for transferring the actual file data or directory listings. This data connection uses TCP Port 20 in Active Mode or a dynamically negotiated port in Passive Mode. This separation ensures that control commands can be sent even while a large file transfer is in progress, maintaining a responsive user experience. Therefore, a successful FTP file transfer inherently requires both the permanent control channel and the temporary data channel, summing up to two connections.

The incorrect option is (1):
One connection is insufficient for standard FTP as it fails to account for the protocol's dual-channel design. Protocols that use a single channel, like HTTP or SFTP (Secure File Transfer Protocol), interleave control and data traffic, which is not how FTP is structured. FTP's two-connection model is fundamental for its operational logic.

The incorrect option is (2):
The number three is incorrect because the File Transfer Protocol is fundamentally defined by its two connections: the control connection and the data connection. There is no standard third connection required by the protocol for a single file transfer operation. Confusing the control and data *ports* (21 and 20) with the connections themselves might lead to this error, but only two logical connections are opened.

The incorrect option is (4):
Four connections is far more than is necessary or defined by the standard FTP protocol. A successful, single FTP session is managed and executed entirely with just the two dedicated connections. Four connections would represent a highly complex or multi-threaded scenario that is outside the scope of a basic protocol definition for a single file transfer.