AWS Well-Architected Framework Principles Questions

Principles and guidelines from the AWS Well-Architected Framework for designing, building, and operating robust, secure, efficient, and cost-optimized systems on AWS. Covers the five pillars—Operational Excellence, Security, Reliability, Performance Efficiency, and Cost Optimization—and related architecture decisions, patterns, and best practices.

MediumTechnical

65 practiced

You are leading a migration of a 15-year-old monolithic on-prem application with heavy DB coupling and 500 TB of data to AWS. Describe a phased migration strategy that maps to rehost, replatform, and refactor approaches. For each phase, list the Well-Architected risks, mitigations, testing strategy, and rollback considerations.

Sample Answer

**Overview (approach)** Phased migration across three waves: Rehost (lift-and-shift) to quickly move workloads, Replatform to gain incremental cloud benefits, and Refactor to fully modernize and decouple the monolith and data. Each phase has explicit risks, mitigations, test plans, and rollback criteria.

**Phase 1 — Rehost (6–12 months)** - Goal: Move app and DB to AWS VMs/EBS (or RDS/Aurora for read replicas) to stop on‑prem aging hardware risk. - Well‑Architected risks: Operational resilience, security posture, network latency, cost sprawl, large-data transfer. - Mitigations: Use Direct Connect + AWS DataSync/Storage Gateway, encrypted transfer, IAM baseline, cost tagging, run read replicas in target VPC. Staged database bulk transfer with physical seeding (Snowball) + CDC (DMS). - Testing: End‑to‑end smoke tests, perf baselining against on‑prem, data integrity checks (checksums), DR failover rehearsal. - Rollback: Maintain cutover window with continuous CDC; if SLA breaches or data mismatch, failback to on‑prem using CDC until final cutover.

**Phase 2 — Replatform (12–18 months)** - Goal: Move critical DBs to managed services (RDS/Aurora), containerize app components, migrate file stores to S3. - Well‑Architected risks: Schema incompatibilities, stateful services, IAM misconfig, increased blast radius. - Mitigations: Schema conversion tool (AWS SCT), blue‑green deployments, network segmentation, parameterized infra via IaC, automated backups and snapshots. - Testing: Integration tests, canary deploys, DB migration dry runs, latency/load tests for managed DBs, S3 lifecycle verification. - Rollback: Blue/green or canary to switch traffic back to rehost environment; RDS snapshots enable point‑in‑time restore; ensure replication lag thresholds.

**Phase 3 — Refactor (18–36 months)** - Goal: Break monolith into services (serverless or k8s), event-driven architectures, streamlining data with lakehouse on S3/Glue/Redshift. - Well‑Architected risks: Functional regressions, data consistency across services, increased operational complexity. - Mitigations: Domain‑driven decomposition, API contracts, consumer‑driven contract testing, event sourcing/CDC patterns, observability (X‑Ray, CloudWatch, OpenTelemetry), staged data migration to lake with governance. - Testing: Contract tests, end‑to‑end business scenario tests, chaos engineering for resilience, data reconciliation jobs. - Rollback: Feature flags to toggle refactored services, fallback to monolith endpoints, transactional compensations for eventual consistency; maintain parallel run until parity.

**Cross‑phase governance & data considerations** - Maintain central migration runbook, pipeline IaC, security baseline (CIS, encryption), continuous cost and performance monitoring. - Data: For 500 TB, combine Snowball for bulk + DMS CDC for delta; validate via checksums and sampling; plan retention and lifecycle.

This phased plan balances speed, risk reduction, and long‑term optimization while providing concrete rollback and verification paths at each stage.

EasyTechnical

72 practiced

As a Cloud Architect, outline the artifacts, stakeholders, and steps you would use to conduct a Well-Architected review for an application team. Include the evidence you would collect (diagrams, cost reports, logs), tools you'd leverage (Well-Architected Tool, Config), and how you'd prioritize remediations.

Sample Answer

**Goal & scope**Define application boundaries, workloads, environment (dev/prod), and review pillars (operational excellence, security, reliability, performance, cost).

**Stakeholders**- Application owners / product manager- Dev leads / SREs / platform engineers- Security & compliance- Finance / FinOps- Cloud operations / network teams- Executive sponsor

**Artifacts & evidence to collect**- Architecture diagram (network, VPCs, subnets, AZs, services)- Deployment pipelines / IaC (CloudFormation/Terraform) snippets- Logs & telemetry: CloudWatch/Prometheus, CloudTrail, application logs- Configuration snapshots: AWS Config, security group ACLs, IAM policies- Cost reports: Cost Explorer, billing reports, resource tags- Metrics: latency, error rates, availability SLOs- Backup/DR runbooks and snapshots- Security scans: vulnerability reports, GuardDuty findings

**Tools to leverage**- AWS Well-Architected Tool (workload questionnaire, export)- AWS Config, CloudTrail, CloudWatch, GuardDuty- Cost Explorer / AWS Budgets / Trusted Advisor- IaC analyzers (tfsec, cfn-nag), SCA tools- Logging/observability stack (ELK, Prometheus + Grafana)

**Steps**1. Kickoff: confirm scope, stakeholders, objectives.2. Collect artifacts (ask for diagrams, IaC, logs, cost exports).3. Automated evidence gathering (Config rules, GuardDuty, Well-Architected Tool scan).4. Conduct pillar-by-pillar workshop with SMEs; map evidence to risks.5. Identify findings, assign severity and owners.6. Prioritize remediations and produce roadmap + quick wins.7. Track progress in sprint boards; re-audit after remediation.

**Prioritization approach**- Rank by (Risk × Business Impact) / Effort — prioritize high-risk, high-impact, low-effort items first.- Enforce policy: security/compliance and reliability (SLA-impacting) are highest priority.- Include cost/efficiency quick wins next (rightsizing, idle resources).- Provide estimated effort, business value, and rollback plan for each remediation.

**Outcome**Deliver a Well-Architected report with mapped evidence, prioritized remediation backlog, owners, timelines, and measurable success criteria (SLOs, cost savings, reduced findings).

EasyTechnical

73 practiced

What key performance metrics should a Cloud Architect track to satisfy the Performance Efficiency pillar for a customer-facing web application? List at least six metrics (e.g., latency percentiles, error rate, throughput) and explain briefly why each is important.

EasyTechnical

68 practiced

Describe the AWS Shared Responsibility Model and map which controls and responsibilities belong to AWS versus the customer. Then explain how a Cloud Architect should reflect this distinction when designing security controls (IAM, encryption, patching, network segmentation) as part of a Well-Architected review.

Sample Answer

**Overview — Shared Responsibility Model**AWS is responsible for the security "of" the cloud (physical infrastructure, hypervisor, regions, AZs, hardware, foundational services). The customer is responsible for security "in" the cloud (OS, applications, data, configurations, identity, client-side encryption, network traffic controls).

**Responsibility Mapping**- AWS: Physical datacenter security, host/hypervisor, physical network, foundational services uptime.- Customer: Guest OS patching, application vulnerabilities, data classification & encryption keys, IAM policies, VPC config, security group rules, logging & monitoring, backup & recovery.- Shared: Managed services (e.g., RDS, S3) — AWS hardens the service; customer configures access, encryption options, and data lifecycle.

**How a Cloud Architect should reflect this in designs**- IAM: Assume customer-owned. Use least privilege, roles for services, permission boundaries, federated SSO, and automated policy testing (IAM Access Analyzer). Design separation of duties between platform and application teams.- Encryption: Architect BYOK/KMS for data-at-rest keys; use TLS for data-in-flight. Decide key rotation, key access policies, and audit logging (CloudTrail+CloudWatch).- Patching: Treat guest OS and application layers as customer responsibility. Prefer managed services or containerization to reduce patch surface; include automated patch windows, vulnerability scanning, and AMI/image pipeline.- Network segmentation: Design multi-AZ VPCs, private subnets, NACLs, security groups, Transit Gateway or Transit VPC for segmentation, and service endpoints to avoid public exposure. Enforce least-privilege network flows and microsegmentation where appropriate.

**Well-Architected review actions**- Document who owns each control, include automated guardrails (AWS Config rules, SCPs, GuardDuty), map compliance requirements, run threat-modeling, and specify monitoring/alerting and incident response playbooks. Recommend managed services where AWS responsibility reduces customer operational burden.

MediumTechnical

78 practiced

As the Cloud Architect, propose a practical governance, training, and tooling rollout plan to adopt AWS Well-Architected best practices across 25 engineering teams with varying cloud maturity within 6 months. Include onboarding, enforcement, support model, and measurable KPIs to track adoption.

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