IntermediatePhone
2 min
API Rate Limiting Basics
APISecurityPerformance
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Interview Question
What is API rate limiting, why is it important, and how is it commonly implemented?
Key Points to Cover
- Rate limiting controls number of requests per client or key
- Prevents abuse, protects backend stability, avoids DDoS
- Implemented via token buckets, leaky buckets, sliding windows
Evaluation Rubric
Defines API rate limiting34% weight
Explains its importance33% weight
Describes common implementation techniques33% weight
Hints
- 💡Think headers like X-RateLimit-Limit and Retry-After.
Common Pitfalls to Avoid
- ⚠️Setting limits too broadly (e.g., global limits instead of per-user/per-endpoint) or too narrowly, leading to either ineffectiveness or over-restriction.
- ⚠️Lack of clear communication: Not providing informative HTTP 429 'Too Many Requests' responses or failing to include a 'Retry-After' header.
- ⚠️Inadequate client identification: Relying solely on IP address for rate limiting, which can be problematic with shared IPs (e.g., NAT, proxies) or easily spoofed.
- ⚠️Implementing static limits without considering varying user tiers (e.g., free vs. premium) or legitimate burst traffic patterns.
- ⚠️High performance overhead: Implementing rate limiting in a way that introduces significant latency or consumes excessive resources, impacting overall API performance.
Potential Follow-up Questions
- ❓How do you handle burst traffic?
- ❓How does rate limiting differ from throttling?
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