What does the -sU option specify in Nmap?

What does the -sU option specify in Nmap?

• A. TCP SYN scan
• B. Ping sweep
• C. UDP port scan
• D. Service version detection

Answer: (C)

The -sU option specifies performing a UDP port scan. It sends UDP probes to the target ports and uses the responses (or lack thereof) to determine whether a port is open, closed, or filtered. Because UDP is connectionless and there’s no handshake, an open port often won’t reply, so lack of response can indicate open or filtered status, while receiving an ICMP Port Unreachable usually means the port is closed. UDP scans tend to be slower and more easily blocked by firewalls, so results can be less reliable and may require adjustments to timing or retries. The other common scan types differ: a TCP SYN scan uses a different option, a ping sweep is used to identify live hosts, and service version detection is done with another option to grab software versions after discovering ports.

The -sU option specifies performing a UDP port scan. It sends UDP probes to the target ports and uses the responses (or lack thereof) to determine whether a port is open, closed, or filtered. Because UDP is connectionless and there’s no handshake, an open port often won’t reply, so lack of response can indicate open or filtered status, while receiving an ICMP Port Unreachable usually means the port is closed. UDP scans tend to be slower and more easily blocked by firewalls, so results can be less reliable and may require adjustments to timing or retries. The other common scan types differ: a TCP SYN scan uses a different option, a ping sweep is used to identify live hosts, and service version detection is done with another option to grab software versions after discovering ports.