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GSEC · Question #226

You work as a Network Administrator for Tech Perfect Inc. The company has a TCP/IP-based network. You have configured a firewall on the network. A filter has been applied to block all the ports. You…

The correct answer is B. 25 D. 110. SMTP (port 25) handles outgoing email transmission between servers, while POP3 (port 110) handles incoming email retrieval by clients. Both ports must be open to enable full email send and receive functionality.

Networking and Core Concepts

Question

You work as a Network Administrator for Tech Perfect Inc. The company has a TCP/IP-based network. You have configured a firewall on the network. A filter has been applied to block all the ports. You want to enable sending and receiving of emails on the network. Which of the following ports will you open? Each correct answer represents a complete solution. Choose two.

Options

  • A80
  • B25
  • C20
  • D110

How the community answered

(35 responses)
  • A
    11% (4)
  • B
    71% (25)
  • C
    17% (6)

Why each option

SMTP (port 25) handles outgoing email transmission between servers, while POP3 (port 110) handles incoming email retrieval by clients. Both ports must be open to enable full email send and receive functionality.

A80

Port 80 is used for HTTP web traffic and has no role in email transmission or retrieval.

B25Correct

Port 25 is the standard SMTP (Simple Mail Transfer Protocol) port used for sending and relaying email between mail servers; without it, outgoing mail cannot be transmitted.

C20

Port 20 is used for FTP (File Transfer Protocol) active mode data transfer, not for email communication.

D110Correct

Port 110 is the standard POP3 (Post Office Protocol version 3) port used by email clients to retrieve incoming messages from a mail server; without it, users cannot receive email.

Concept tested: SMTP and POP3 port numbers for email services

Source: https://learn.microsoft.com/en-us/exchange/mail-flow-best-practices/message-flow-best-practices

Topics

#email protocols#SMTP#POP3#port numbers

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