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System Design Architectures

Interactive technical blueprints, capacity estimates, database sharding strategies, and visual flowcharts for the top 30 system design interview questions.

Target Architectures
Infrastructure Component

Content Delivery Network (CDN)

Globally distributed network of edge servers caching static files (JS, images, videos) closer to the user to bypass origin bottlenecks.

1. System Requirements

Functional
  • Cache static and dynamic content at edge proxy locations.
  • Resolve requests from the geographically closest Edge server via Anycast routing.
  • Support compression (Gzip, Brotli) and cache invalidation APIs.
Non-Functional / SLA
  • Ultra-low latency connection handshakes (< 15ms).
  • Scale to handle massive bandwidth spikes (Terabits per second).

2. Scale & Resource Estimates

Throughput: Millions of concurrent connections distributed across hundreds of global PoPs (Points of Presence).

Storage & RAM: Cached static files are stored on SSDs at edge servers. Size scales with media libraries.

3. System API Endpoints

// Origin Request Resolution
HTTP GET /assets/hero.jpg
DNS resolves to closest Edge PoP IP
If (Edge Cache Hit) -> Return assets
If (Edge Cache Miss) -> Fetch from Origin server, Cache, Return

4. Database Schema Design

Cache-Control Headers:
Cache-Control: public, max-age=31536000, immutable
ETag: "W/df382-990a424"

5. Interactive High-Level Architecture

graph TD User[User in London] -->|Request Asset| Edge[Edge Server London] Edge -->|Cache Hit| Return[Return Static Asset] Edge -->|Cache Miss| Origin[Origin App Server in US] Origin -->|Populate Edge Cache| Edge

6. Scalability Deep Dive & Bottlenecks

CDNs use Anycast routing to advertise a single IP address from multiple global locations. When a user requests a file, BGP routing routes the packets to the closest physical Point of Presence (PoP). CDNs utilize Cache-Control headers (like s-maxage) to define expiration times. For dynamic caching, CDNs evaluate caching rules at the edge to compress and minify content.

7. Production Scaling Strategies

Brotli Compression: Reducing asset transfer sizes by up to 25% compared to gzip to speed up edge downloads.

Origin Shielding: Positioning a dedicated high-capacity proxy layer in front of the origin servers to protect them from cache misses.

Invalidation Webhooks: Releasing instant purge requests to globally invalidate files in < 150ms.

8. Runnable Production Starter Code

Scaffold