Which protocol is designed for efficient transfer of large files and uses separate control and data connections?

• A. File Transfer Protocol (FTP)
• B. Hypertext Transfer Protocol (HTTP)
• C. Simple Mail Transfer Protocol (SMTP)
• D. Secure Copy (SCP)

Answer: (A)

FTP is the protocol designed for efficient transfer of large files and it uses two separate connections: a control connection for commands and a separate data connection for the actual file data. The control channel handles login, directory listings, and file-type negotiations, while the data channel carries the content of the files being transferred. This separation allows large transfers to proceed without being blocked by command traffic and lets the transfer be optimized independently from the control communication. It also supports options like binary mode to ensure exact file contents, and restart capabilities to resume interrupted transfers.

For context, HTTP focuses on web resources and typically relies on a single connection for each request/response, not specialized for large file transfer. SCP provides secure copying over SSH but uses a single secure channel rather than a separate data/control split. SMTP is for email transfer, not file transfer. The two-connection design and file-transfer orientation make FTP the best fit for efficiently moving large files.