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CompTIA A+ Core 1 (220-1201)NetworkingEasy

A technician is configuring an email server so that outgoing mail can be relayed correctly. Which of the following TCP ports is used by default for sending email between mail servers?

  1. A110
  2. B25
  3. C143
  4. D21
Show answer & explanation

Correct answer: B. 25

SMTP (Simple Mail Transfer Protocol) uses TCP port 25 to send and relay email between mail servers. Port 21 is FTP, 110 is POP3, and 143 is IMAP, all of which are unrelated to sending outbound mail.

Why the other options are wrong

  • A. Port 110 is used by POP3 for retrieving email.
  • C. Port 143 is used by IMAP for retrieving email.
  • D. Port 21 is used for FTP control connections, not email.

SMTP Port 25

SMTP is the protocol used to send and relay email between mail servers, operating by default on TCP port 25.

  • SMTP = Simple Mail Transfer Protocol
  • Default port: TCP 25
  • Used for sending, not retrieving, mail

Memory trick: 'S'MTP 'S'ends mail on port 25.

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