Which of the following file-transfer protocols uses TCP and establishes two…
2010
Which of the following file-transfer protocols uses TCP and establishes two separate logical connections—one for control and one for data—between a local client and a remote server?
Answer: A. FTP — ConceptConnection-oriented application protocols can separate session control from payload transfer. When one TCP connection carries commands and replies…
- A.
FTP
- B.
TFTP
- C.
TELNET
- D.
NFS
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Correct answer: A
Concept
Connection-oriented application protocols can separate session control from payload transfer.
When one TCP connection carries commands and replies while another TCP connection carries file data, the protocol uses a dual-connection architecture.
Application
FTP follows this architecture: its control connection remains open for commands and replies, while a separate data connection carries directory listings or file contents. Therefore, the protocol described is FTP.
Contrast
TFTP is a lightweight file-transfer protocol that uses UDP rather than a pair of TCP connections.
TELNET provides remote terminal access through a single TCP connection.
NFS provides remote file-system access through RPC and is not organized as control and data connections for a file-transfer session.
Cross-check
RFC 959 describes FTP with distinct control and data connections, which matches both conditions in the question.
Result
FTP