Cybersecurity

DDoS

Definition

A Distributed Denial-of-Service (DDoS) attack is a malicious attempt to disrupt the normal traffic of a targeted server, service or network by overwhelming the target or its surrounding infrastructure with a flood of Internet traffic.

Why It Matters

DDoS attacks are a major threat to the availability of online services. By overwhelming a target with traffic, they can effectively take a website or application offline for hours or even days.

Contextual Example

An attacker uses a "botnet" (a network of thousands of infected computers) to send a massive flood of requests to an e-commerce website. The website's servers become overwhelmed and are unable to respond to legitimate customers, making the site unavailable.

Common Misunderstandings

  • A "DoS" (Denial of Service) attack comes from a single source, while a "DDoS" (Distributed Denial of Service) attack comes from many sources at once, making it much harder to block.
  • Cloud providers and services like Cloudflare offer DDoS mitigation services.

Related Terms

Last Updated: December 17, 2025