System Design Card 427 — Rate Limiting / Assess
Concern
Rate limiting protects multi-tenant fairness, abuse resilience, and downstream stability. An API gateway or notification ingress often needs both per-user and per-tenant controls.
What Assess means for this concern
In BASIC, the Assess step is where you identify the main architectural pressures and choose which trade-offs are actually important. For Rate Limiting, that means the candidate should make this concern visible at the right moment instead of bolting it on at the end.
Design move
A good move is to compare plausible approaches before committing. Tie the concern back to the user flow, the workload, and the dominant trade-off. That keeps the design grounded and makes it easier for the interviewer to follow why a cache, queue, replica, partition, or rate limiter is actually necessary.
Common miss
The miss is discussing scale without discussing protection against pathological clients. BASIC helps because the staged flow keeps this concern proportional to the prompt and connected to the rest of the architecture.
BASIC prompt
“When I reach the Assess stage, how does Rate Limiting change the architecture, the trade-offs, or the review checklist?”