Networks & Defense
Denial of Service
Also: DoS, DDoS, distributed denial of service
An attack that makes a service unavailable by exhausting a resource it needs.
In more detail
Services have finite bandwidth, CPU, memory and connection slots. A flood fills the pipe; a cheap-request attack sends small inputs that cost the server a lot of work, as in HTTP/2 Rapid Reset. DDoS comes from many sources at once. Defences are layered: upstream filtering, rate limits, timeouts, caching, capped autoscaling and patching.