Related chapter
Interview Approaches
A 7-step framework for working with system design problems.
This part is a practical unit on System Design. Now it already contains 27 full-fledged case tasks: from infrastructure primitives to product systems with a large number of dependencies and scenarios. The purpose of this section is to learn how to identify requirements, select architectural primitives, make informed trade-offs, and explain the evolution of the solution as the load grows.
Scale and coverage
Total in parts
27 cases
From basic infrastructure tasks to domain-specific product systems.
Infrastructure cases
11 tasks
Gateway, storage, CDN, limiter and other universal building blocks.
Product cases
16 problems
Marketplace, real-time, search, fintech, communications and geoservices.
Focus of training
NFR + trade-offs
Latency, throughput, consistency, availability, reliability and cost.
Case catalog
Infrastructure tasks
Fundamental services and platform components that are found in any system.
Product cases
Domain-specific tasks where user scenarios, business constraints and complex data flows are important.
Marketplace and bookings
Content and communications
Platforms and search
Fintech and transactions
Diversity Matrix: What exactly are you training?
Latency and real-time scenarios
Tasks where low-latency paths, fan-out, push mechanisms and predictable response time are critical.
Data-intensive and indexing
Ingestion flows, deduplication, indexing, ranking and high throughput requirements.
Storage, durability and delivery
Scenarios with metadata/data split, replication, fault tolerance and data distribution.
Transactions and Business Correctness
Cases where consistency boundaries, idempotency, anti-fraud and the correct state of orders are important.
Recommended training trajectories
Interview sprint (7-10 days)
A quick route to cover basic patterns and typical interview questions.
Platform / infrastructure focus
For platform and backend engineers: storage, data paths, resilience and control plane.
Product systems focus
For designing consumer products with a large number of user scenarios.
Why infrastructure first, then business
The order is structured as a learning path: first, universal primitives, then their application in products with more complex scenarios and domain restrictions.
1. Basic blocks
Rate limiter, gateway, storage and CDN form the foundation - without them, business systems will not scale.
2. Pattern combination
Using product tasks, we learn to combine cache, queues, sharding, consistency and degradation modes.
3. Real restrictions
Domain cases add UX, SLA, anti-fraud, compliance and cost constraints - this is closer to real work.
How to work with tasks
- First, clarify the requirements and specify the assumptions.
- Highlight the key NFRs: latency, throughput, consistency, availability and cost.
- Build a high-level architecture and identify critical components.
- Make a deep dive into the most difficult place and explain the trade-offs.
- Talk through the evolution: from MVP to scaling and operational support.
If you need a reference framework, take a look Design principles for scalable systems And Interview Approaches.
For additional hands-on practice on interview-style problem framing and depth, use System Design Primer (problem set) and High Scalability.