A closed port responds to a SYN scan with an RST packet, so if no packet is received, the best guess is that the port is open.

Question

Quizplus · Accepted Answer

The statement is incorrect. A closed port responds to a SYN scan with an RST packet, while an open port responds with a SYN-ACK packet. If the scanner receives no response at all, it is more likely that the port is filtered, meaning that a firewall or other network device is blocking the traffic.

A Closed Port Responds to a SYN Scan with an RST