CompTIA Security+ (SY0-501) — Question 466

A technician must configure a firewall to block external DNS traffic from entering a network.
Which of the following ports should they block on the firewall?

Answer options

• A. 53
• B. 110
• C. 143
• D. 443

Correct answer: A

Explanation

The correct answer is A, port 53, as it is used for DNS traffic. Ports 110 and 143 are used for email protocols (POP3 and IMAP respectively), while port 443 is used for HTTPS traffic, and blocking these would not prevent DNS traffic.