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Lessons (40)

• VPC Endpoints, Transit Gateway and Hybrid Networking

  … Endpoint policies restrict what can be done through an endpoint: json { "Statement": [{ "Effect": "Allow", "Principal": " ", "Action": ["s3:GetObject …

• Troubleshooting Playbook

  … what did the app say?] D -- E[Check Service, endpoints, DNS, policies] E -- F[Check node and cluster …

• Domains, Load Balancers and HTTPS

  … Once the browser learns the endpoint address, it connects to the endpoint. This explains why a correct DNS …

• DynamoDB Modeling, RDS Scaling and Data Resilience

  … Check [RDS Proxy endpoints](https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/rds-proxy-endpoints.html). Deliverable: document …

• N+1 Queries, Loading & Pagination

  … Ask which fields the endpoint truly renders. Offset versus cursor pagination Offset asks the database to walk past …

• Networking, DNS and Traffic Routing

  … Failover must include connection errors, retry behavior and healthy old endpoints where possible; DNS TTL is not a …

• Vertical Slice Architecture & the Modular Monolith

  … place order"] direction TB a1[endpoint] -- a2[validate] -- a3[domain model] -- a4[(repository)] end subgraph S2["Slice: order …

• Cost Optimization and the Well-Architected Framework

  … add S3 and DynamoDB gateway endpoints; use interface endpoints for heavy services; keep traffic within an AZ. 3 …

• Internals, Upgrades, Resilience and Interview Questions

  … Liveness vs readiness vs startup probes? Liveness restarts a stuck container, readiness removes a pod from Service endpoints …

• VPC Networking Without the Confusion

  … An S3 gateway endpoint can instead provide access to S3 through VPC routing without requiring a NAT path …

• REST vs GraphQL vs gRPC

  … Each dish (endpoint) comes as the kitchen designed it. Simple and predictable, but you might get extra sides …

• Capacity, Availability, Latency and CAP

  … Define latency and availability targets for specific endpoints. An aggregate average can hide failed checkout requests. 3. Allow …

• Python Web APIs: FastAPI and Django

  … FastAPI with Pydantic models, dependencies and async endpoints, and Django with its ORM, migrations, admin and Django REST …

• Backend Design Scenarios

  … The failure policy depends on the endpoint: Endpoint If limiter is unavailable --- --- Login, password reset, expensive public API …

• REST API Design

  … application/vnd.shop.v2+json Query /users?version=2 Non-breaking changes (adding a field, adding an endpoint …

• Debug Latency Like an Investigator

  … Compare before/after traces for the same endpoint and split latency into pool wait, SQL execution and downstream …

• Timeouts, Retries & Backpressure

  … During an incident it takes three seconds; retries occupy every worker and healthy endpoints become slow. What must …

• Cluster Networking, DNS and NetworkPolicies

  … ready pod IPs] E -- P1[Pod A] E -- P2[Pod B] EndpointSlices list the ready pod IPs behind …

• Observability and Incident Response

  … Start with endpoint success rate and latency split by release, region and dependency. Identify the incident’s scope …

• CloudFront: Faster Websites and Safer File Delivery

  … OAC works with a regular S3 bucket origin, not an S3 website endpoint. Website endpoints have different behavior …

• Deploying & Operating Microservices

  … Remove or rename a field Add a new endpoint Change a field's type Add a new event …

• Product-Scale Frontend Patterns

  … durable local queue - retry when online - idempotent server endpoint show “pending sync” reconcile success or conflict Never silently …

• Code Profiling

  … a faster benchmark with tiny sample data is not proof of a better endpoint. Profile I/O separately …

• 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 …

• Services and Ingress: Let Traffic Find Your App

  … api kubectl get svc shop-api kubectl get endpointslices kubectl describe svc shop-api The most common cause …

• Database Internals, Replication and Scaling

  … More replicas do not increase the single-writer write budget automatically. Check your understanding Which read endpoints need …

• API Contracts, Gateways and Security

  … combination of user, API key, IP and expensive endpoint. - Keep secrets in a secret manager, rotate them, and …

• Resilient Service Calls: Retries, Breakers and Load Shedding

  … Measure attempts per original request, queue age, successful throughput and unrelated-endpoint latency; a low downstream call count …

• AWS Interview Questions: Clear Answers

  … capability, and a check of the real public endpoint after deployment. Scenario: a website is slow after a …

• GitOps, Progressive Delivery and Observability

  … shop-api } endpoints: - port: http path: /metrics Alert on symptoms users feel (error rate, latency, saturation) rather than …

• C4 Architecture Diagrams: Context, Container, Component and Code

  … Do not put classes, folders, endpoints or Kubernetes Pods in the first two diagrams. That is too much …

• Capacity Planning, SLOs and Error Budgets

  … can operate. The problem in context A checkout endpoint processes 1,000 requests/s at peak and has …

• Practical Project: Deploy a Real CRM App on EKS

  … The Service has endpoints: kubectl -n dev get endpoints crm-core . 3. The Ingress created an ALB with …

• How a Web Request Works

  … DB[(Database)] js // A minimal Node.js (Express) endpoint app.get("/products/:id", async (req, res) = { const product …

• A WhatsApp OTP Is Only Single Use If You Make It So

  … Respond the same way for every reason so the endpoint does not reveal which. Why this is safe …

• API Gateway, BFF & Service Discovery

  … one endpoint shaped exactly for the home screen app.get("/mobile/home", async (req, res) = { const [user, orders …

• Scaling, Load Balancing & Rate Limiting

  … alive is not ready Use separate endpoints and meanings: - Liveness: the process is running and should not be …

• Authentication, Authorization & API Security

  … resource access - [ ] Rate limiting on login and expensive endpoints - [ ] Secrets in a vault or env vars, never in …

• NestJS Core Concepts

  … NestJS when… --- --- A small service or a few endpoints A large app with many modules and developers You …

• Containers at Scale: ECS Deep Dive and EKS

  … Plans for the stable base. - Keep the API endpoint private or restricted by CIDR, and enable control plane …