Provyn Prep · System Design competency
Scaling & reliability in the System Design assessment
Scaling & reliability is one of the areas a Provyn System Design credential scores separately, so a recruiter can see it on its own rather than averaged into one number. This guide explains what it covers, how it is tested and what to practice.
What it covers
Scaling a service: load balancing, rate limiting, queues, capacity estimates and keeping latency under control.
Topics in the practice set for this area
- scaling
- rate limiting
- queues / messaging
- capacity planning
- load balancing
- latency
How it is tested
In the timed assessment, questions in this area use these formats: matching, multiple choice, put the steps in order, short answer, system design canvas. Each attempt draws its own set of questions, and this area gets its own sub-score on the credential when the attempt includes enough questions from it. The assessment questions themselves are never published; the practice set below is written separately for study.
What to practice
- Do a back-of-the-envelope capacity estimate for requests, storage and bandwidth.
- Compare two rate-limiting algorithms and where each would run.
- Explain how a queue smooths traffic spikes and what it costs in latency.
Try a practice question
From the free practice set (8 questions in this area). Answers and explanations are in the practice set.
- Horizontal scaling means:
- Read replicas serve which workload?
- When designing a rate limiter, leaky-bucket vs token-bucket:
Practice before the real thing
Both are free and use practice questions only, never questions from the real assessment.
More System Design study guides
Last reviewed 2026-10-06.