AWS Well-Architected Framework
The official 6 pillars, 57 architectural questions, and 139 best-practice answers extracted verbatim from the AWS Well-Architected Tool workload System Design Preperation. Master the core invariants and trade-offs expected in Senior SDE & Principal System Design interviews.
Architectural Pillars
Official Questions
Verbatim Best Practices
Architecture Guides
Perf vs Cost vs Maint
Unlike a multiple-choice quiz where only 1 option is correct, every Best Practice listed under each question is an official AWS architectural answer. In the AWS Well-Architected Tool, checking all best practices achieves 100% compliance. In an Amazon System Design interview, your score is determined by how many of these best practices you proactively design for and defend. Omitting any item labeled High Risk creates an architectural vulnerability that interviewers will probe.
In Amazon Bar Raiser and Senior SDE interviews, evaluators score candidates directly against the 6 pillars. Every design decision involves trade-offs across Performance Efficiency (latency, throughput), Cost Optimization (data transfer, compute waste), and Maintainability / Reliability (blast radius, operational runbooks). When presenting a design, always articulate both what you gain and what you give up across these three axes.
Amazon Architecture & Interview Playbooks7 Comprehensive Guides
Complete AWS verbatim guides, distributed systems invariants, 3-axis trade-off playbooks, and Amazon interview scenarios with end-to-end solutions.
AWS Well-Architected Framework & System Design Playbook
Architecture Map & Amazon Preparation Overview
Executive map of the 6 AWS Well-Architected Framework pillars, 57 official workload questions, and Amazon Senior SDE Bar Raiser scoring rubric.
Distributed Systems Fundamentals & Core Invariants
CAP, PACELC, Raft Consensus, and Jitter Mechanics
Deep dive into distributed consensus, CAP/PACELC trade-offs, shuffle sharding, exponential backoff with full jitter, idempotency keys, and blast radius isolation.
The 3-Axis Trade-off Analysis Playbook
Performance vs. Cost vs. Maintainability Framework
Structured frameworks to articulate and defend trade-offs across Performance, Cost, and Maintainability in Amazon System Design interviews.
Reliability & Fault Tolerance
REL 1 through REL 13 Deep Dive & Resilience Patterns
Exhaustive analysis of REL 1-13: cell-based architectures, circuit breakers, multi-AZ/multi-region failovers, RPO/RTO disaster recovery, and chaos engineering.
Performance Efficiency & Cost Optimization
PERF 1-5 & COST 1-11 Compute, Storage & Networking
Pillars 2 & 3: DynamoDB Single-Table Design, compute form factors (Lambda vs Fargate vs EC2), NAT Gateway traps ($0.045/GB), and cross-AZ data transfer charges.
Operational Excellence, Security & Sustainability
OPS 1-11, SEC 1-11 & SUS 1-6 Production Standards
Pillars 4, 5, & 6: The 4 Golden Signals, canary rollouts with automated alarms, IAM least privilege, KMS Envelope Encryption, and Graviton3 carbon efficiency.
Amazon System Design Interview Scenarios & Answers
Prime Day Flash Sale, Distributed Sagas, and Global Tables
End-to-end architectural solutions, Mermaid diagrams, and verbatim interview defense scripts for Amazon Prime Day flash sales, distributed order sagas, and real-time tracking.
The 6 Architectural Pillars(Click to filter or explore)
Reliability
The ability of a workload to perform its intended function correctly and consistently when it's expected to, including operating and testing the workload through its total lifecycle.
Performance
The ability to use computing resources efficiently to meet system requirements, and to maintain that efficiency as demand changes and technologies evolve.
Cost Optimization
The ability to run systems to deliver business value at the lowest price point.
Operational Excellence
The ability to support development and run workloads effectively, gain insight into their operations, and continuously improve supporting processes and procedures.
Security
The ability to protect data, systems, and assets to take advantage of cloud technologies to improve your security posture.
Sustainability
The ability to continually improve the environmental sustainability impacts of your cloud workloads by minimizing resource consumption and maximizing utilization.
Recommended Answers (Official AWS Best Practices Checklist)
Every best practice below is an official answer to incorporate into your system design:
Audit default quotas for network throughput, IOPS, and API rate limits across all dependencies.
Ensure quota increases are replicated across all production accounts and failover regions.
Design systems using cellular architecture and partitioning when hard unchangeable limits are reached.
Proactively track usage against thresholds using AWS Service Quotas alerts.
Use Service Quotas APIs to programmatically request increases prior to anticipated traffic spikes.
Verify surviving AZs or Regions have sufficient quota to absorb 100% of shifted failover load.
Pre-allocating high quotas avoids abrupt 429 throttling during traffic surges but does not replace client-side backpressure.
Requesting higher soft quotas is free in AWS, but over-provisioning reserved concurrency (e.g. Lambda) incurs idle cost.
Cellular partitioning around fixed limits introduces routing complexity but permanently bounds blast radius.
Recommended Answers (Official AWS Best Practices Checklist)
Every best practice below is an official answer to incorporate into your system design:
Use redundant Direct Connect connections or multi-tunnel IPsec VPNs.
Avoid single points of failure in hybrid cloud gateway routing.
Allocate sufficiently sized CIDR blocks (/16) to prevent IP exhaustion during auto-scaling.
Keep databases and compute isolated from public internet exposure across 3+ Availability Zones.
Ensure VPC CIDRs do not conflict across interconnected accounts and Transit Gateways.
Multi-AZ placement ensures fault tolerance but introduces 1-2ms inter-AZ latency for synchronous cross-AZ calls.
Cross-AZ traffic costs $0.01/GB each way ($0.02/GB total). Design for AZ affinity where possible.
Transit Gateway simplifies hub-and-spoke routing across hundreds of VPCs, eliminating complex VPC peering meshes.
Recommended Answers (Official AWS Best Practices Checklist)
Every best practice below is an official answer to incorporate into your system design:
Segment into decoupled microservices or service-oriented architectures based on domain boundaries.
Adhere to Single Responsibility and Domain-Driven Design (DDD) to isolate change impact.
Expose explicit, backward-compatible REST or gRPC contracts to decouple clients from implementations.
Microservices introduce network RPC latency overhead compared to monolith in-process method calls.
Separate compute fleets per microservice can have higher baseline idle cost without serverless scale-to-zero.
Microservices allow independent deployments and localized failure domains, dramatically accelerating team velocity.