Which type of scan uses ICMP ECHO Requests to detect live hosts?

• A. ICMP ping sweep
• B. Ping trace
• C. Tracert
• D. Smurf scan

Answer: (A)

Sends ICMP Echo Requests across a range of addresses to see which devices answer. That's what a ping sweep does: you probe many IPs with pings, and any host that replies is identified as live or reachable. The method hinges on the basic ping idea—an Echo Request followed by an Echo Reply.

This approach is especially useful because it gives a quick map of active devices before deeper analysis. However, some hosts or networks block ICMP or rate-limit replies, so not every live device may respond.

Why the other options don’t fit: traceroute (tracert) aims to map the route to a specific destination by eliciting Time Exceeded responses from routers along the path, not to enumerate all live hosts in a network. The smurf scan uses spoofed ICMP Echo Requests sent to a broadcast address to amplify traffic, which is an abuse/DoS tactic rather than a method to list live hosts. The term ping trace isn’t a standard, widely used method for discovering live hosts in a network.