An internal tool serves a few dozen requests per day, mostly during business hours, with occasional idle days. Which compute approach minimizes cost?
A.An always-on m5.large EC2 instance
Always-on instances bill continuously regardless of use.
B.AWS Lambda behind API Gateway, paying only per request
Correct. Per-request serverless billing eliminates idle cost.
C.A Dedicated Host reserved for the tool
Dedicated Hosts are the most expensive, isolation-driven option.
D.An ECS cluster with two always-running tasks
Always-running ECS tasks bill like always-on servers.
Why this answer
For sparse, intermittent traffic, Lambda + API Gateway scales to zero and bills per request and duration — typically pennies per day versus paying for idle always-on capacity.
Correct answer: B · Last reviewed 2026-10-25
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