A company runs a production application on a fleet of Amazon EC2 instances. The application reads messages from an Amazon Simple Queue Service (Amazon SQS) queue and processes the messages in…

Question

Options

• AUse only Spot Instances to handle the maximum capacity required.
• BUse only Reserved Instances to handle the maximum capacity required.
• CUse Reserved Instances to handle the baseline capacity. Use Spot Instances to provide
• DUse Reserved Instances in an EC2 Auto Scaling group to handle the minimum capacity.

• A
  13% (3)
• B
  4% (1)
• C
  78% (18)
• D
  4% (1)

Explanation

AWS guidance is to cover steady baseline with commitments (Reserved Instances or Savings Plans) and use EC2 Spot Instances for burst capacity to minimize cost. Spot provides up to 90% discounts and is well-suited to fault-tolerant, queue-based workloads; interruptions are handled by replacing capacity automatically while messages remain durably in SQS. Using only Spot (A) risks capacity gaps; only RIs sized for peak (B) wastes cost during low demand. Option D scales on backlog but uses On-Demand for bursts, which is more expensive than Spot. With C, baseline capacity (RIs) keeps processing continuously (no downtime), and Spot adds cost-efficient throughput during spikes, aligning with Well-Architected cost and reliability patterns for queue

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