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Question 98Asked in BEL PE Computer Science, 20 Dec 2025 (5:00 PM)

During an SMTP session, a client communicates with a mail server to send an email.

During an SMTP session, a client communicates with a mail server to send an email. Consider the following sequence of SMTP commands and responses observed in a network trace: S: 220 mail.example.com ESMTP Postfix C: HELO client.host.com S: 250 mail.example.com Hello client.host.com C: MAIL FROM:<alice@example.com> S: 250 OK C: RCPT TO:<bob@example.net> S: 550 No such user here C: RCPT TO:<carol@example.net> S: 250 OK C: DATA S: 354 End data with <CR><LF>.<CR><LF> C: [message body] C: . S: 250 Message accepted for delivery C: QUIT S: 221 Bye Based on the SMTP protocol rules, which of the following statements is most accurate about this interaction?
  1. AThe client successfully delivered the message to all recipients, including Bob and Carol.
  2. BThe server rejected the entire message because one recipient was invalid.
  3. CThe SMTP session was invalid because the client did not issue the EHLO command.
  4. DThe client successfully sent the message, but it will only be delivered to Carol, since Bob's address was rejected.
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Correct answer: (D) The client successfully sent the message, but it will only be delivered to Carol, since Bob's address was rejected.

From BEL PE Computer Science PYQ, 20 Dec 2025 (5:00 PM)

This is question 98 of BEL PE Computer Science PYQ, 20 Dec 2025 (5:00 PM). See all questions of this paper with answers, or attempt the paper as a timed online test to get your score and all-India rank.