What characterizes a DDoS attack?

A DDoS attack, or Distributed Denial of Service attack, is characterized by an overwhelming surge of traffic directed at a specific service or network, rendering it unable to respond to legitimate user requests. The primary goal of this attack is to disrupt the availability of the targeted service, making it inaccessible to its intended users.

During a DDoS attack, multiple compromised systems (often part of a botnet) flood the target with excessive requests or data, effectively saturating the bandwidth or overloading servers. This wreaks havoc on network resources and can lead to service outages, loss of revenue, and damage to reputation.

The other options do not align with the nature of a DDoS attack. Securing a network from intrusions or fortifying system security involves protective measures, while methods for increasing server capacity focus on enhancing performance rather than causing disruption. These activities are typically aimed at ensuring service availability, which is in direct opposition to the objectives of a DDoS attack.