Billing, Pricing, and Support (12%)
This domain tests your ability to select the right pricing model for a workload, identify the correct billing or cost-management tool for a given scenario, and distinguish between AWS Support plan tiers. Expect scenario-based questions where you must pick the most cost-effective option or identify which tool solves a described problem.
AWS Pricing Principles
Three core principles underpin every pricing question:
- Pay-as-you-go: No upfront commitment; you pay only for what you consume.
- Save when you commit: Reserved Instances and Savings Plans offer discounts (up to ~72%) in exchange for 1- or 3-year commitments.
- Pay less when you use more: Tiered pricing applies to services like S3 and data transfer—the more you use, the lower the per-unit rate.
Data transfer into AWS is free. Data transfer out to the internet costs money. Data transfer between services in the same region over private IP is generally free or very low cost.
Free Tier
Three distinct types—know the difference:
| Type | Duration | Example |
|---|---|---|
| 12-month free | From account creation | 750 hrs/mo EC2 t2.micro or t3.micro |
| Always free | No expiration | 1M Lambda requests/mo, 25 GB DynamoDB |
| Trials | Short-term per service | 90 days Amazon Inspector |
Trap: The 12-month free tier starts from account creation date, not first use. After 12 months, standard rates apply automatically.
EC2 Purchasing Options
This is the highest-yield subtopic in this domain. Match the use case to the option:
- On-Demand: Unpredictable workloads, short-term, no commitment. Highest per-hour cost. No upfront payment required.
- Reserved Instances (RIs): Steady-state, predictable workloads (e.g., production databases). 1- or 3-year terms. Standard RIs give the largest discount but can't change instance family. Convertible RIs allow attribute changes but offer a smaller discount.
- Savings Plans: More flexible than RIs. Compute Savings Plans apply across EC2, Fargate, and Lambda regardless of instance family or region. EC2 Instance Savings Plans are scoped to a specific family/region. Both require a 1- or 3-year commitment on $/hr spend.
- Spot Instances: Spare AWS capacity, up to 90% discount. AWS can reclaim with a 2-minute warning. Use for fault-tolerant, stateless, or batch workloads. Never use for databases or anything requiring guaranteed availability.
- Dedicated Hosts: Physical server you control; required for bring-your-own-license (BYOL) software (e.g., Windows Server, SQL Server per-socket licensing). Most expensive option.
- Dedicated Instances: Instances on hardware not shared with other AWS accounts—but you don't control the specific host. Cheaper than Dedicated Hosts.
Decision rule: Spot = cheapest + interruptible. Dedicated Host = compliance/licensing. Reserved/Savings Plans = predictable long-running. On-Demand = everything else.
S3 Pricing
You are charged for: storage (GB/mo by storage class), requests (GET, PUT, etc.), and data transfer out. Key storage class cost tradeoffs:
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