A final-revision summary for SAA-C03. Study aid only — no notes in the proctored exam.
Well-Architected Framework — six pillars
Operational Excellence · Security · Reliability · Performance Efficiency · Cost Optimisation · Sustainability.
Core services by category
| Category | Services |
|---|---|
| Compute | EC2, Auto Scaling, Lambda, ECS/EKS, Fargate |
| Storage | S3 (object), EBS (block), EFS (file), FSx |
| Database | RDS/Aurora (SQL), DynamoDB (NoSQL), ElastiCache, Redshift |
| Networking | VPC, subnets, security groups, NACLs, Route 53, CloudFront, ELB |
| Security | IAM, KMS, Secrets Manager, WAF, Shield |
| Integration | SQS (queue), SNS (pub/sub), EventBridge |
When to use which storage
| Need | Service |
|---|---|
| Object storage, web assets, backups | S3 |
| Block storage for one EC2 instance | EBS |
| Shared file storage across instances | EFS |
| Archival, lowest cost | S3 Glacier |
SQL vs NoSQL
| Use | Service |
|---|---|
| Relational, complex queries | RDS / Aurora |
| Key-value, massive scale, low latency | DynamoDB |
| In-memory caching | ElastiCache |
Pricing models (EC2)
On-Demand (flexible) · Reserved / Savings Plans (commit, cheaper) · Spot (cheapest, interruptible).