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101 · Question #491
101 Question #491: Real Exam Question with Answer & Explanation
The correct answer is A: During an active FTP session. In active FTP mode, the client opens a listening port for the data connection, temporarily acting as a server for the data channel.
Question
In which scenario does the client act as a server?
Options
- ADuring an active FTP session
- BWhen an SMTP connection
- CDuring an SMTP connection
- DWhen browsing websites
Explanation
In active FTP mode, the client opens a listening port for the data connection, temporarily acting as a server for the data channel.
Common mistakes.
- B. SMTP is a client-initiated protocol where the sending host always connects outbound to port 25 on the mail server; the client never listens for or accepts incoming connections.
- C. During an SMTP connection, the client pushes mail to the server by initiating the TCP connection; the client does not open a listening port for the server to connect back to.
- D. When browsing websites, the client sends HTTP/HTTPS requests to the web server and only receives responses; all connections are outbound from the client.
Concept tested. Active FTP mode client data channel role
Reference. https://www.rfc-editor.org/rfc/rfc959
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