Rounds

High-Level Design Round

System design assessment covering distributed systems, scalability, and architectural trade-offs

Overview

The HLD round assesses a candidate's ability to design large-scale distributed systems. Expect to whiteboard architecture diagrams, discuss trade-offs between consistency and availability, and reason about failure modes.

Round Structure (60 min)

TimePhaseSignals
0-5 minProblem & ScopeAsks about scale, users, SLAs
5-15 minHigh-Level ArchitectureIdentifies core components quickly
15-35 minDeep DiveData model, API contracts, storage choices
35-50 minScaling & ReliabilitySharding, replication, failure handling
50-60 minTrade-offs & MonitoringCAP awareness, observability

Scoring Rubric

Dimension1234
ScopingNo questions; wrong assumptionsSome clarificationGood scoping; identifies MVPExpert scoping; phased approach
ArchitectureMonolith with no reasoningBasic client-serverAppropriate microservices splitElegant; justified component boundaries
Data DesignNo data model discussionBasic schema, wrong DB choiceGood schema + justified DB selectionPolyglot persistence; access pattern driven
ScalabilityNo awareness of scaleMentions caching/LBConcrete sharding + replication strategyBack-of-envelope math; bottleneck analysis
ReliabilityNo failure discussionAcknowledges failuresDiscusses retries, circuit breakersChaos engineering mindset; graceful degradation
  1. Design URL Shortener (TinyURL)
  2. Design Twitter / News Feed
  3. Design WhatsApp / Chat System
  4. Design YouTube / Video Streaming
  5. Design Uber / Ride Sharing
  6. Design Notification System
  7. Design Rate Limiter (distributed)
  8. Design Search Autocomplete
  9. Design Distributed Cache
  10. Design Payment System