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Lessons (38)

• VPC Networking Without the Confusion

  … Check its default route, NAT gateway placement, internet-gateway route from the NAT's public subnet, and outbound …

• State, Remote Backends, and Locking

  Share state through S3, enable native locking, migrate safely, and protect recovery data. Why state exists A resource …

• VPC Endpoints, Transit Gateway and Hybrid Networking

  Keep traffic private, cut NAT costs, connect many VPCs, link to on-premises networks, and troubleshoot with flow …

• Hash Maps & Sets

  … Grouping → map of lists Group anagrams: ["eat","tea","tan","ate","nat","bat"] → [["eat","tea","ate"],["tan","nat"],["bat …

• Cost Optimization and the Well-Architected Framework

  … 2. NAT gateway data processing : add S3 and DynamoDB gateway endpoints; use interface endpoints for heavy services; keep …

• Choosing a Programming Language

  … Go, Rust"] S1[source] -- C1[compiler] -- B1[native binary] -- CPU1[CPU] end subgraph INT["Interpreted: Python"] S2[source …

• Atomic Design & Component Libraries

  … A button needs native semantics, keyboard behavior, focus visibility, and a disabled state. Prefer the browser's native …

• DBMS Foundations, Keys & Normalization

  … File systems store bytes but do not naturally enforce cross-file integrity or safe shared updates. Q14-Q17 …

• REST vs GraphQL vs gRPC

  … SSE / WebSockets separately Subscriptions ✅ Built in Browser support ✅ Native ✅ Native ⚠️ Needs gRPC-Web Performance Good Good Excellent Learning …

• AWS Interview Questions: Clear Answers

  … A NAT route can permit outbound IPv4 access for private workloads without making them directly reachable by unsolicited …

• Containers at Scale: ECS Deep Dive and EKS

  … ECS or EKS? ECS EKS --- --- --- Control plane AWS-native, no extra fee Managed Kubernetes, hourly fee per cluster …

• Architecture Patterns at Scale

  … Peer-to-peer Direct decentralized sharing Discovery, trust, NAT traversal Start with the smallest shape that meets the …

• Design System Operations

  … Do not replace native controls unnecessarily, and test keyboard navigation in the final styling—not only in the …

• Real-Time, Pub/Sub, Webhooks and CDC

  … WebRTC Direct low-latency media/data Needs signaling, NAT traversal and fallback Pub/Sub One event to many …

• AWS Databases: Choose the Right One

  … Relational storage is a natural starting point. A delivery-status service might instead need only “get the latest …

• Cluster Networking, DNS and NetworkPolicies

  … Pods can reach all other pods without NAT . 3. Agents on a node can reach all pods on …

• AI Specialties and Real-World Examples

  … damaged parcels Image preprocessing, CNNs, vision transformers, augmentation Natural language processing Text → labels or structured information Route tickets …

• L — Liskov Substitution Principle

  … So inheritance seems natural: js class Rectangle { setWidth(w) { this.width = w; } setHeight(h) { this.height = h; } area …

• Delivery Guarantees: At-Most, At-Least & Exactly Once

  … make the operation naturally idempotent (an upsert with the final value) await db.query( "INSERT INTO order status …

• Backend Languages: Node.js, Go, Python & Rust

  … NestJS] Q -- High concurrency, simple deploys,<br/ cloud-native tools G[Go] Q -- AI/ML or data work …

• SQL vs NoSQL Databases

  … Data is relational (customers ↔ orders ↔ products) Data is naturally a self-contained document or key-value You need …

• Message Queues & RabbitMQ

  … memory streams Lightweight background jobs in Node.js NATS Lightweight pub/sub Low-latency messaging Key takeaways - Queues …

• Finding Service Boundaries with DDD

  … its own model. - A bounded context is the natural boundary for a microservice, with its own data and …

• CQRS & Event Sourcing

  … exact sequence of events that caused a bug 📣 Natural fit for events Events are already the source of …

• Event-Driven Architecture

  … events to consumers Kafka, RabbitMQ, SNS/SQS, EventBridge, NATS Event consumer Reacts to events it's interested in …

• Resilience, Disaster Recovery and Multi-Region Design

  … cases. - Data replication is the hardest part; use native cross-region features. - Protect backups in a separate account …

• Normalization & Denormalization

  … identify the key and dependencies The natural row key is (order id, product id) because one order can …

• Practical Project: Deploy a Real CRM App on EKS

  … Create the cluster and node group eksctl creates the VPC, public and private subnets, NAT gateway, IAM roles …

• Vertical Slice Architecture & the Modular Monolith

  … update price"] direction TB c1[endpoint] -- c2[handler] -- c3[(db)] end This fits naturally with CQRS : queries read …

• CloudFront: Faster Websites and Safer File Delivery

  … When you deploy changed filenames such as app.abc123.js , visitors naturally receive the new file. Avoid frequently …

• Safe AWS Deployments with IaC and CI/CD

  … many cloud providers; stores state remotely CloudFormation AWS-native templates and stacks CDK Write AWS infrastructure using programming …

• Run Containers on AWS with ECR and ECS

  … Private task subnets need outbound access to ECR and related dependencies, through NAT or appropriate VPC endpoints. An …

• Structural Patterns: How to Connect Objects

  … Flyweight saves memory. - JavaScript's higher-order functions and built-in Proxy make these patterns short and natural.

• AWS: Start Here

  … an idle virtual machine, load balancer, database, or NAT gateway can still cost money. Storage can continue to …

• Python Web APIs: FastAPI and Django

  … ORM + migrations Admin UI ❌ ✅ generated from models Async Native ( async def ) Supported, ORM mostly sync API docs Automatic …

• Domain-Driven Design: Tactical Patterns

  … a business rule that doesn't naturally belong to one entity export class ShippingCostCalculator { calculate(order: Order, destination …

• L6 Production Debugging Casebook

  … distinguish live heap, native memory, direct buffers and a too-small heap/container limit. 6. Rename a live …

• Backend Design Scenarios

  … Partition by a natural access boundary such as tenant or time when queries can use partition pruning and …