What is a DDoS attack?

A DDoS (Distributed Denial of Service) attack floods a target (server, network, service) with massive amounts of traffic from many distributed sources (a botnet), overwhelming its capacity to respond to legitimate requests. Types: Volumetric attacks: saturate bandwidth (UDP floods, ICMP floods). Protocol attacks: exploit protocol weaknesses (SYN floods exhaust TCP connection tables). Application-layer attacks: target the web application (HTTP flood, Slowloris — sending slow partial requests to keep connections open). Mitigation: CDN/scrubbing services (Cloudflare, AWS Shield, Akamai) that absorb and filter attack traffic. Rate limiting, anycast routing, IP reputation filtering, and CAPTCHA for application-layer attacks. DDoS attacks are often used as diversions while other attacks occur.