EC2’s purchasing options trade commitment and reliability for price, and the exam constantly asks you to match the workload to the cheapest option that still meets its needs.
Quick decision guide
On-Demand — no commitment, full price; unpredictable or short workloads. Reserved / Savings Plans — 1-3 year commitment, big discount; steady always-on workloads. Spot — up to ~90% off but can be reclaimed; fault-tolerant, interruptible work. Match the keyword: “interruptible” = Spot, “steady” = Reserved, “unpredictable/short” = On-Demand.
Test yourself
A steady production web server runs 24/7 for years. Which purchasing option minimizes cost?
- On-Demand
- Spot Instances
- Reserved Instances or a Savings Plan
- Dedicated Hosts
👉 Click to reveal the answer & explanation
Correct answer: C. Reserved Instances / Savings Plans give the best discount for steady, always-on workloads via a 1-3 year commitment. On-Demand (A) is pricier for constant use; Spot (B) can be reclaimed (bad for a steady production server); Dedicated Hosts (D) are for compliance/licensing.
Related topics
Amazon EC2 · Savings Plans vs Reserved · Auto Scaling
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