Design a Netflix-like streaming platform
Overview
This question evaluates a candidate's competence in large-scale system architecture, distributed systems, and end-to-end media streaming operations, encompassing authentication and profiles, cataloging and recommendations, ingestion/transcoding, DRM and adaptive bitrate delivery, CDN and storage strategies, session management, APIs, failover, observability, and cost optimization. Commonly asked in System Design interviews to assess reasoning about scalability, availability, low-latency playback, and operational trade-offs, it belongs to the system design and media-streaming domain and tests both conceptual understanding of architectural trade-offs and practical application via capacity estimation and operational considerations.
System Design: Netflix‑Like Video Streaming Platform
Context
Design a large-scale video streaming platform that supports web, mobile, and TV clients for millions of concurrent viewers worldwide. The system should prioritize availability, low-latency playback, security, and cost efficiency.
Assume:
- Peak: 5–10 million concurrent streams globally.
- Target startup latency < 2 seconds; low rebuffering; 99.9%+ availability for playback.
- Mix of on-demand VOD content; live not required (optional considerations welcome).
Requirements
Design the system and cover the following components:
- User Authentication and Profiles
- Sign-in, sessions, MFA, device limits, parental controls, multiple profiles per account.
- Content Catalog and Metadata
- Titles, seasons/episodes, genres/tags, availability windows, rights/regions, subtitles/audio tracks.
- Search and Personalized Recommendations
- Full-text search, browse pages, personalized rows, cold-start handling.
- Video Ingestion and Transcoding Pipeline
- Secure uploader, QC, per-title encoding, thumbnails, captions, packaging to HLS/DASH.
- DRM and Adaptive Bitrate Streaming
- Widevine/FairPlay/PlayReady, license services, CMAF, HLS/DASH manifests, LL-HLS optional.
- CDN and Edge Caching Strategy
- Multi-CDN, edge authorization, origin shielding, cache warming/purges.
- Storage and Geo-Replication
- Masters vs renditions, object storage layout, lifecycle tiers, cross-region replication.
- Playback Session Management
- Session creation, concurrency enforcement, heartbeats, QoE metrics, resume playback.
- APIs and Service Discovery
- External API gateway, internal gRPC, schema, rate limits, idempotency, service mesh.
- Multi-Region Failover and Data Consistency
- Active-active vs active-passive, routing, data models with consistency choices.
- Observability and A/B Testing
- Metrics/traces/logs, QoE SLOs, experimentation platform, guardrails.
- Cost Optimization
- Encoding ladder strategy, codec choices, storage lifecycle, CDN offload, compute efficiency.
Deliver a high-level architecture and justify key trade-offs. Include back-of-the-envelope capacity estimates and call out pitfalls and edge cases.
Solution
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