Which scan involves sending UDP packets and observing a UDP response to infer host activity?

Which scan involves sending UDP packets and observing a UDP response to infer host activity?

• A. A ping sweep
• B. UDP Ping Scan
• C. ICMP ECHO ping scans
• D. Angry IP Scanner

Answer: (B)

The key idea here is detecting live hosts using UDP traffic. A UDP Ping Scan sends UDP packets to the target and watches for a UDP reply (or for an ICMP response like Port Unreachable if the port is closed). If a UDP response is observed, it shows the host is active because the device processed the UDP packet and responded. This method relies on UDP rather than ICMP, which is why it’s distinct from other common reachability checks. This explains why the UDP Ping Scan is the best fit: it specifically uses UDP probes and looks for UDP-based feedback to infer that a host is up. In contrast, a ping sweep or ICMP ECHO ping scans rely on ICMP Echo replies, not UDP, and Angry IP Scanner is a general tool that can perform various methods but isn’t defined by this UDP-response probing concept.

The key idea here is detecting live hosts using UDP traffic. A UDP Ping Scan sends UDP packets to the target and watches for a UDP reply (or for an ICMP response like Port Unreachable if the port is closed). If a UDP response is observed, it shows the host is active because the device processed the UDP packet and responded. This method relies on UDP rather than ICMP, which is why it’s distinct from other common reachability checks.

This explains why the UDP Ping Scan is the best fit: it specifically uses UDP probes and looks for UDP-based feedback to infer that a host is up. In contrast, a ping sweep or ICMP ECHO ping scans rely on ICMP Echo replies, not UDP, and Angry IP Scanner is a general tool that can perform various methods but isn’t defined by this UDP-response probing concept.