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Security Operations · Foundational

Denial of Service (DoS)

An attack that makes a system or network unavailable to legitimate users by exhausting resources or crashing services.

Definition

DoS attacks target availability through volumetric flooding, protocol exhaustion (such as SYN floods) or application-layer requests that consume server resources. A single source is used, distinguishing it from DDoS. Rate limiting, filtering and patching mitigate it.

Example

Sending malformed packets that crash a vulnerable service.

Exam tip

DoS affects the A in the CIA triad.

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