What is characteristic of a DDoS attack?

A Distributed Denial of Service (DDoS) attack is characterized by its origin from multiple computers that are often part of a botnet. This network of compromised devices floods a target, such as a server or website, with excessive traffic, overwhelming it and making it unavailable to legitimate users. The distribution of the attack across numerous sources helps to obscure the true origin of the attack and makes it more difficult to mitigate, as blocking a single IP address or even a few addresses will not effectively mitigate the flood of traffic coming from multiple locations.

The other provided options do not accurately describe the nature of a DDoS attack, which reinforces why the correct choice emphasizes the simultaneous involvement of many computers in the attack. This distributed nature is a key factor that distinguishes DDoS attacks from traditional Denial of Service attacks, which typically originate from a single source.