Certified Ethical Hacker (CEH v10) — Question 142

During an Xmas scan, what indicates a port is closed?

Answer options

• A. RST
• B. SYN
• C. ACK
• D. No return response

Correct answer: A

Explanation

An RST (reset) packet indicates that the port is closed because it is the response sent by the target to signal that it has rejected the connection attempt. In contrast, a SYN packet is used to initiate a connection, an ACK packet is used to acknowledge received packets, and a lack of response may indicate that the port is filtered rather than closed.