pertaining to or being an incident in which a computer or computer network is disabled, disrupting access or service: a website hit by a denial-of-service attack; unintentional denial-of-service problems.
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Denial of Service (DoS) attack A DDoS (Distributed Denial of Service
Denial-of-service attack – Wikipedia
Architecture of Distributed Denial of Service (DDoS) attack
Denial of Service and DDoS Attacks: How to Prevent Them
What is a Denial of Service Attack 2017 | full explained in detail