Which type of attack occurs when a botnet is used to transmit requests from an NTP server to overwhelm the target?

The situation described involves a botnet, which is a network of compromised computers that can be used to perform coordinated attacks. In this case, the attack leverages a Network Time Protocol (NTP) server to send an overwhelming volume of requests to a target. This is characteristic of a Distributed Denial of Service (DDoS) attack, where multiple sources (the bots in the botnet) send requests simultaneously, aiming to exhaust the target's resources and make it unavailable to legitimate users.

DDoS attacks exploit the capabilities of both the botnet and the amplification effects of certain protocols (like NTP), significantly increasing the attack traffic received by the target. The use of a single NTP server to send large amounts of unsolicited or amplified traffic towards the target exemplifies the distributed nature of the tactic, as the flood of requests comes from many compromised devices rather than a single source.

In contrast, other types of attacks listed, such as On-Path (which refers to interception of communications), Denial of Service (which typically involves a single source), and Replay (which involves the re-sending of valid data transmissions) do not fit the described scenario, as they do not involve multiple sources or the specific use of botnets and amplification techniques