Basic Concept: DoS attacks overwhelm AI systems by sending excessive requests that exhaust computational resources, memory, or bandwidth, preventing legitimate users from being served. The primary defense against volume-based attacks is throttling the rate at which requests can be processed. CompTIA SecAI+ Exam Objectives identify rate limiting as the key DoS mitigation control for AI systems.

Why B is Correct: Rate limiting directly addresses the root mechanism of DoS attacks by restricting the number of requests any single client or IP address can submit within a defined time window. By enforcing request quotas, rate limiting prevents attackers from generating the request volume necessary to overwhelm the system while preserving capacity for legitimate users. It is the most direct and effective preventive control against DoS attacks on AI APIs and services.

Why A is Wrong: Model guardrails inspect and filter the content of prompts and responses for policy compliance and safety. They operate at the semantic content level, not at the request volume level, and cannot prevent resource exhaustion from high-volume request flooding.

Why C is Wrong: End-to-end encryption protects the confidentiality and integrity of data in transit. Encrypted DoS traffic is just as damaging as unencrypted traffic; encryption does not limit request rates or prevent resource exhaustion.

Why D is Wrong: Access controls restrict who can interact with the system, which can reduce the potential attacker pool. However, authenticated users and compromised accounts can still launch DoS attacks, and access controls alone cannot prevent high-volume attacks from authorized sources.