Week 1 was the week of abstractions. The five axes of CALMS, the four DORA metrics, the six pillars of Well-Architected, the AWS DevOps tool map, and multi-account governance. Taken separately, each is a massive book of its own, but within DOP-C02 scenarios, two or three of them always show up bundled together. Accelerating from "one deployment per quarter → one per day" is not solved by just installing Automation tooling — blast radius, account separation, signature verification, rollback automation, and observability all get pulled up along with it.
Today we cement that bundled problem-solving with 12 scenarios. Each question was built by weaving together two or three concepts from Days 1-4, and the explanations are written assuming you'll face exactly the same form of question in the exam room. In the end, what Week 1 wants to teach is one sentence: "DevOps is a system for flowing code quickly and safely, and AWS's tools, account structures, and metrics are the parts for translating that system into code."
| Axis | Diagnostic question | Symptoms when weak | Top-priority AWS tools |
|---|---|---|---|
| Culture | Who gets blamed during incidents? | Incident cover-ups, repeated identical incidents | Blameless COE, Incident Manager, Chatbot |
| Automation | How many manual steps remain? | Frequency stagnation, MTTR explosion, human error | CodePipeline + CodeBuild + CodeDeploy + SSM Automation |
| Lean | How many days until PR merge? | WIP accumulation, runaway lead time | Trunk-based dev, AppConfig feature flags |
| Measurement | How do you know a change's effect? | "Gut feel" decisions, KPI gaming | CloudWatch Metrics + EMF + DORA dashboard |
| Sharing | Do one team's insights flow onward? | Same mistakes recur in other teams | Service Catalog, Proton, Wiki |
| Metric | Signal of weakness | First-line prescription (AWS) |
|---|---|---|
| Deployment Frequency ↓ | Once per quarter, once per month | CodePipeline automation + small batches + AppConfig flags |
| Lead Time ↑ | Commit→prod 2 weeks+ | Remove Manual Approval + CodeBuild cache + monorepo split |
| Change Failure Rate ↑ | 30%+ incident rate | Canary + CloudWatch alarm auto-rollback + pre-deploy hooks |
| MTTR ↑ | Days after an incident | EventBridge → SSM Runbook + Incident Manager |
| Pillar | Scenario keywords | DevOps perspective |
|---|---|---|
| Operational Excellence | "automation," "observability," "runbooks" | CALMS's A + M |
| Security | "least privilege," "shift-left," "auditing" | DevSecOps |
| Reliability | "RTO/RPO," "Multi-AZ/Region," "self-healing" | Auto-rollback + chaos |
| Performance | "latency," "throughput" | Profiler, instance types |
| Cost | "waste," "budget," "Spot" | Right-sizing, autoscale |
| Sustainability | "carbon," "renewable energy" | Region selection, ARM/Graviton |
NotAction is mandatory.In the exam room, consciously walk through these four steps.
🎯 Scenario: A report comes in that "there are so many Slack alerts they're being ignored." What is the problem? Not the tooling — it's a broken Measurement definition. Making every metric an alert without SLOs/SLIs produced alert fatigue. The answer is not adding tools but defining SLOs + reducing noise with Composite Alarms + Error Budget-based classification. A case where CALMS's M axis was quantitatively satisfied but qualitatively collapsed.
Click a choice to reveal the answer and explanation.
Question 1
A large fintech is pushing to accelerate from "one deployment per quarter → one per week." Current state: dev/staging/prod separated only by VPC in a single AWS account, humans deploying directly from the console with no CodePipeline, and an average of 8 hours to recover when incidents occur. Which CALMS diagnosis + prioritized prescription is most appropriate?
Question 2
A company deploys identical workloads to us-east-1 and eu-west-1. Its users are global and GDPR compliance is mandatory. Operating in a single account, it is highly concerned about blast radius during incidents. After adopting Organizations, which OU structure is most appropriate?
Question 3
A company is adopting the SaaS monitoring tool Datadog. Datadog needs access to metrics in our AWS account. From a security + automation standpoint, what is the most appropriate setup?
Question 4
A company reported this problem: "deployment frequency is Elite-level at 5 per day, but Change Failure Rate is 40%." Which of the following actions is most effective?
Question 5
A global company deploying across 5 regions wants to manage all accounts' CloudTrail logs with centralization + tamper prevention. What is the most appropriate architecture?
Question 6
A company is building CI/CD in a multi-account environment. CodePipeline lives in the Shared Services account, and the deployment target is the Prod account. It must deploy to an ECS service in the Prod account and uses artifacts encrypted with a KMS key. What is the most accurate permission setup?
Question 7
A company wants to enforce "no EC2/RDS/S3 operations in any region other than ap-northeast-2 and us-east-1" across all accounts. What must you absolutely watch out for when writing the SCP?
Question 8
A company runs an EKS cluster in the Prod account and deploys GitOps-style via ArgoCD. In a single-cluster scenario, where is the most appropriate place to put ArgoCD?
Question 9
A company received the requirement "visualize DORA metrics on a dashboard." What is the most appropriate data pipeline in an AWS environment?
Question 10
A company wants to enforce an automatic "read-only mode during specific hours (weekends, 0-6 a.m.)" on the Production account. What is the most appropriate mechanism?
Question 11
Which organizational model most accurately implements Werner Vogels's "You Build It, You Run It" principle in an AWS environment?
Question 12
A company received the demand: "one team ran up \$30,000 in a month in a sandbox account. Make sure it never happens again." What is the most effective combination of actions?
The five things we've covered so far — the DevOps operating model, CALMS/DORA, W-AF, the tool map, and multi-account — form the background for all of DOP-C02 Domains 1-6. Starting next week we dive into Domain 1 (SDLC) in earnest, and every CodePipeline / CodeBuild / CodeDeploy scenario you'll meet there is solved on top of these two questions:
Keep these two questions in mind, and next week's topics — trunk-based development, OIDC federation, CodeArtifact, code signing — will start to look not like "tools to memorize separately" but like "different parts of the same thinking frame."