Several hundred infected computers simultaneously attacked your organization's server, rendering it useless to legitimate users. What kind of attack is this an example of?

This scenario describes a Distributed Denial of Service (DDoS) attack. In a DDoS attack, multiple systems are used to flood a target server with overwhelming traffic or requests, effectively incapacitating it and preventing legitimate users from accessing it. This is often achieved through a network of compromised computers, known as a botnet, which can simultaneously send a large volume of requests to the targeted server.

The key aspect here is that the attack originates from various locations, utilizing many infected machines concurrently to disrupt the server's availability. This distributed nature distinguishes it from other attack types, as it leverages the collective power of numerous devices rather than a single source.

While a botnet is related and may encompass the technology behind a DDoS, it specifically refers to the network of infected machines, not the action of attacking the server itself. A Man-in-the-Middle (MITM) attack involves intercepting and potentially altering communication between two parties, not overwhelming a server. A rainbow table attack involves cracking passwords through precomputed tables and does not pertain to server availability issues. Thus, the DDoS attack correctly identifies the nature of the attack on the server as described.