SAA-C03 practice question: EC2 purchasing options (3 of 3)
Design Cost-Optimized Architectures A free question from our original SAA-C03 practice exam. Try it, then open the answer to see why each option is right or wrong.
A company spends a steady amount every hour on compute and expects this to continue for at least 3 years.
Over that time it plans to move many workloads from Amazon EC2 to AWS Fargate and AWS Lambda, switch EC2 instance families as new generations arrive, and possibly move some workloads to another AWS Region. It wants a discount that follows these changes automatically, without manual exchanges.
Which purchase option should it choose?
Choose one answer.
AA. Buy EC2 Instance Savings Plans for the current instance families in the current Region, with a 3-year term.
BB. Buy Convertible Reserved Instances with a 3-year term, and exchange them whenever instance families change.
CC. Buy Standard Reserved Instances with a 3-year term for the instance types that the company runs today.
DD. Buy Compute Savings Plans with a 3-year term and an hourly commitment that matches the steady baseline.
Show the answer and explanation
Answer: D
A. Wrong: EC2 Instance Savings Plans give the deepest Savings Plans discount, but each plan is tied to one instance family in one Region. They do not apply to Fargate or Lambda, so the discount would shrink as workloads move or change family. Learn more: Savings Plans types (opens in a new tab)
B. Wrong: Convertible Reserved Instances can be exchanged for another instance family, operating system or tenancy, but only by manual exchanges and only within the same Region. They never apply to Fargate or Lambda, so they miss two of the company's plans. Learn more: Exchange Convertible Reserved Instances (opens in a new tab)
C. Wrong: Standard Reserved Instances give a large discount for a fixed instance configuration in one Region. They cannot follow a change of instance family or Region, and they do not apply to Fargate or Lambda, so much of the commitment would go unused. Learn more: Compute Savings Plans and Reserved Instances (opens in a new tab)
D. Right: Correct. Compute Savings Plans apply automatically to EC2 usage in any instance family, size, Region, operating system or tenancy, and also to Fargate and Lambda. The company commits to an hourly spend, and the discount follows the workloads as they change. Learn more: Compute Savings Plans and Reserved Instances (opens in a new tab)
Explanation
Only Compute Savings Plans apply automatically across instance families and Regions and to Fargate and Lambda, in exchange for an hourly spend commitment over 1 or 3 years. EC2 Instance Savings Plans and Reserved Instances can give bigger discounts, but they are tied to EC2, to a Region, and (except by manual exchange) to an instance family.
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