101 · Question #576
Which two destination pods should be used in a default active FTP Session? (Choose two)
The correct answer is B. TCP 20 D. TCP 21. Active FTP uses TCP port 21 for the command channel and TCP port 20 as the server-side source port for the data connection.
Question
Which two destination pods should be used in a default active FTP Session? (Choose two)
Options
- AUDP 20
- BTCP 20
- CTCP 22
- DTCP 21
- EUDP 21
How the community answered
(25 responses)- B92% (23)
- C4% (1)
- E4% (1)
Why each option
Active FTP uses TCP port 21 for the command channel and TCP port 20 as the server-side source port for the data connection.
FTP uses TCP for all connections to ensure reliable, ordered delivery of commands and data; UDP port 20 is not used in any part of the FTP protocol.
In active FTP, the server initiates the data transfer connection from its TCP port 20 toward the client-specified ephemeral port after receiving a PORT command. TCP port 20 is the well-known data port that identifies the active FTP data channel on the server side.
TCP port 22 is the reserved port for SSH (Secure Shell) remote access and has no role in standard FTP sessions.
TCP port 21 is the well-known destination port where the FTP server listens for the client's initial control connection. All FTP control commands such as USER, PASS, PORT, and RETR are exchanged over this TCP 21 connection throughout the entire session.
FTP relies exclusively on TCP connections for both control and data channels; UDP port 21 is not defined or used in any FTP operation.
Concept tested: Active FTP session control and data port usage
Source: https://www.ietf.org/rfc/rfc959.txt
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