Under the Hood of Netflix's Architecture

Hi Inner Circle,

Happy Thursday!

Today, we are diving into a platform that serves 247M+ users globally - where every design decision matters.
Let’s peek under the hood and see what powers Netflix — and how it can inspire your own architecture and interview prep.

1. Core Building Blocks

Netflix's architecture is a layered system built to scale and perform under pressure.

Let's dive into the core cloud services:

AWS Services (Netflix runs mostly on AWS, but the concepts apply to any cloud)

Core Architecture Layers

Compute

• Microservices deployed on EC2 for flexibility

• Container workloads in Titus (Netflix’s own container orchestration, similar to Kubernetes)

• Event-driven tasks running serverless functions (e.g., AWS Lambda)

Network

• Open Connect — Netflix’s private CDN with servers at ISPs around the world

• AWS Global Accelerator for smart routing based on latency

• Elastic Load Balancers for spreading traffic evenly

Storage

• Amazon S3 for originals (raw + encoded media)

• Cassandra/DynamoDB for metadata (e.g., video titles, categories)

• EVCache/Redis for lightning-fast lookups

• RDS for relational data (subscriptions, payments)

AI/ML

• Recommendation engine (what to watch next)

• Adaptive bitrate streaming (adjusts quality to your internet speed)

• Thumbnail generation that A/B tests images to increase clicks

• ML-based compression to save bandwidth without losing quality

Security & Compliance

• Zero-trust networking — every request is verified, nothing is assumed safe

• IAM with least privilege — services only get permissions they truly need

• Automated key rotation so credentials are never stale

• Real-time anomaly detection for account & service abuse

Observability & Reliability

• Centralized logging

• Distributed tracing (Mantis, Zipkin) for debugging across services

• Service Level Objectives (SLOs) for performance targets

• Chaos testing to validate recovery under failure

2. Performance & Scale — Lessons from Netflix

Netflix’s scale isn’t about “buying big servers.” It’s about designing for the unpredictable so the experience stays smooth from 10 users to 10 million watching at once.

Global Edge Delivery

• Push content closer to users (via Open Connect CDN) to reduce buffering

Multi-Region Active-Active

• Operate from multiple AWS regions at the same time

• If one region fails, traffic instantly shifts to another without downtime

Auto-Scaling for the Unpredictable

• Scale out quickly during big releases (e.g., Stranger Things release)

Performance-Driven Storage Choices

• Object storage (cheap & scalable) for raw video

• NoSQL for quick access to metadata

• In-memory cache for hot data

• Relational DB for structured, transactional data

Observability as a First-Class Citizen

• Detailed metrics for every microservice

• Alerting before the user notices an issue

Chaos Testing for Confidence

• Tools like Chaos Monkey shut down services randomly in production to test resilience

Scaling Principles Netflix Lives By

• Horizontal Scaling → Add more small servers instead of one giant server

• Proximity Matters → Place data close to the user for lower latency

• Optimize Everything for Delivery → From video encoding to routing decisions

• Embrace Failure → Expect things to break, design so it doesn’t hurt users

• Automate Deployments → Continuous delivery reduces risk and speeds fixes

• Data-Driven Decisions → Everything from thumbnail choice to server placement is backed by metrics

• Smart Traffic Management → Use API gateways (Zuul) and service discovery (Eureka) to route traffic efficiently

3. Top 6 Cloud Strategies to Learn from Netflix

1. Global CDN First – Push content to the edge to reduce latency.

2. Microservices at Scale – Break systems into small, independent services.

3. Multi-Region Active-Active – Always have a backup running live.

4. Chaos Engineering – Simulate disasters before they happen.

5. Automated Scaling – Expand and shrink capacity with demand.

6. AI in the Workflow – Use ML to boost both infrastructure efficiency and user experience.

4. Interview Prep — Whiteboarding This Architecture

If you’re asked to design a “Netflix for X”:

1. User Flow → device → app → API Gateway → services → CDN → playback

2. Core Components → compute, network, storage, AI

3. Trade-Offs →

   • CDN vs fetching from origin

   • NoSQL vs relational DB

   • Multi-region cost vs reliability

4. Resilience → failover, retries, monitoring, chaos testing

5. Thought-Starters & Research Questions

• If a region fails, how does traffic reroute instantly?

  → Hint: Use global DNS with automated health checks.

• How is data synced across multiple active regions?

  → Hint: Asynchronous database replication across active-active regions

• What’s the cost difference between heavy caching vs live fetches?

  → Hint: Caching reduces expensive API calls and network costs.

• How do you scale AI personalization for millions without creating bottlenecks?

  → Hint: Decouple with event-driven, asynchronous processing layers.

• Which other industries could use this exact architecture pattern?

  → Hint: Social media, gaming, e-commerce, and FinTech.

TL;DR:

Ultimately, the lessons from Netflix aren't just about what specific tools to use.

They’re about a mindset of designing for resilience, automation, and scale from the very beginning.

From local scripts to full-scale cloud automation, these principles are a core part of modern DevOps. So go ahead, embrace failure, automate (where required), and get ready to build something that's truly bulletproof.

Thanks for stopping by!

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