220-801 · Question #786
Which of the following ports MUST be open to transport files across a network using FTP?
The correct answer is A. 21. FTP uses TCP port 21 as its control channel to establish and manage file transfer sessions.
Question
Which of the following ports MUST be open to transport files across a network using FTP?
Options
- A21
- B53
- C110
- D443
How the community answered
(54 responses)- A93% (50)
- B4% (2)
- C2% (1)
- D2% (1)
Why each option
FTP uses TCP port 21 as its control channel to establish and manage file transfer sessions.
FTP operates using a two-channel model: port 21 is the control port used to send commands and receive responses, and port 20 (active mode) or a negotiated high port (passive mode) is used for the actual data transfer. Port 21 must be open for any FTP session to be established.
Port 53 is used by DNS for name resolution and has no role in FTP file transfers.
Port 110 is used by POP3 for retrieving email from a mail server.
Port 443 is used by HTTPS for encrypted web traffic, not FTP.
Concept tested: FTP control port assignment
Source: https://learn.microsoft.com/en-us/iis/configuration/system.applicationhost/sites/site/ftpserver/connections
Topics
Community Discussion
No community discussion yet for this question.