Covered the basics: volumetric floods, protocol abuse, application-layer stuff.
Start by defining a denial-of-service attack and distinguishing it from a distributed denial-of-service attack. Then, structure your answer around a layered mitigation strategy, covering network, application, and architectural defenses, and discuss trade-offs such as cost, complexity, and user experience.
Pro tip: Emphasize that mitigation is about raising the cost for attackers and maintaining availability, not achieving perfect prevention. Mention that at Google-scale, defenses like rate limiting and load balancing are automated and adaptive, and tie your answer to real-world examples like Google's Project Shield.
Clearly explain that a DoS attack aims to make a service unavailable by overwhelming it with traffic or exploiting vulnerabilities, and that DDoS uses multiple distributed sources to amplify the attack.
Briefly classify attacks into volumetric (e.g., UDP floods), protocol (e.g., SYN floods), and application-layer (e.g., HTTP floods) to show breadth of understanding.
Describe defenses at different layers: network (firewalls, scrubbing centers, anycast), application (rate limiting, CAPTCHAs, WAFs), and architectural (CDNs, load balancing, auto-scaling, redundancy).
Explain that mitigations involve trade-offs: rate limiting may block legitimate users, scrubbing centers add latency and cost, and auto-scaling can be expensive. Highlight the need to balance security, availability, and user experience.
Summarize that a layered, adaptive approach with monitoring and incident response is key, and mention that no single solution is sufficient.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.