DevOps, SRE & Cloud Interview · Cloud Fundamentals · Lesson 2 of 2
The Well-Architected pillars
AWS's Well-Architected Framework gives six pillars to reason about any cloud design. Interviewers use them as a checklist to see whether you think beyond 'it works'.
- Operational Excellence: run and monitor systems, automate changes, learn from incidents (IaC, runbooks, observability).
- Security: least privilege, encryption in transit and at rest, defense in depth, traceability.
- Reliability: recover from failure, scale horizontally, remove single points of failure, test recovery (multi-AZ, backups).
- Performance Efficiency: use the right resource types and sizes, scale elastically, adopt managed services.
- Cost Optimization: pay only for what you need — right-size, use spot/reserved capacity, turn off idle resources.
- Sustainability: minimize the environmental impact of your workloads (efficient utilization, right regions).
Everything is a trade-offThe pillars often pull against each other — more reliability (multi-region) costs more; tighter security can add latency. A good design names the trade-off it chose and why, rather than pretending one axis is free.
◆ Lock it in
- Six pillars: Operational Excellence, Security, Reliability, Performance Efficiency, Cost Optimization, Sustainability.
- Reliability = remove single points of failure, span AZs, test recovery.
- Use the pillars to show you weigh trade-offs, not just make it work.
Feynman drill — say it out loudList the Well-Architected pillars and give one design decision that improves reliability but hurts cost.
Step 1 rate your confidence · Step 2 pick your answer
Which Well-Architected pillar most directly covers removing single points of failure and testing recovery?
Step 1 — how sure are you?