What occurs during a Denial of Service (DoS) attack?

During a Denial of Service (DoS) attack, the goal is to overwhelm a targeted website or online service by flooding it with an excessive amount of requests from multiple sources. This surge in traffic can either be orchestrated from many computers under the control of an attacker (in the case of a Distributed Denial of Service, or DDoS, attack) or from a single source. When the website or service receives more requests than it can handle, it cannot effectively respond to legitimate user requests, often resulting in a shutdown or severe degradation of service.

This makes it inaccessible to users who genuinely want to interact with it, thereby disrupting normal operations. Understanding the mechanics of this attack is crucial for developing appropriate defenses and mitigation strategies to ensure continuous availability and security of online resources. Options involving excessive access from a single computer or denial of access at the personal user level do not capture the essence of what constitutes a Denial of Service attack. Additionally, an attack aimed at improving site performance contradicts the very nature of DoS, which is focused on denial, not enhancement.