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Answer: Use Reserved Instances for the production EC2 instances. Use On-Demand Instances for the development and test EC2 instances.
## Explanation **Correct Answer: B** **Analysis of the scenario:** 1. **Production EC2 instances**: Run 24 hours a day with predictable usage patterns. This makes them ideal candidates for **Reserved Instances** which offer significant cost savings (up to 75% compared to On-Demand) for steady-state workloads. 2. **Development and test EC2 instances**: Run for at least 8 hours each day, with automation planned to stop them when not in use. These have intermittent usage patterns, making **On-Demand Instances** the most suitable choice because: - They can be started and stopped as needed - No long-term commitment required - Pay only for what you use - Flexible for environments that don't run continuously **Why other options are not optimal:** **A. Spot Instances for production**: Spot Instances are not suitable for production workloads that require high availability and run 24/7, as they can be interrupted with short notice (2 minutes). Production environments need reliability. **C. Spot blocks for production**: Spot blocks (now called Spot Instances with defined duration) provide capacity for a specified duration but still carry the risk of interruption. They're better for batch jobs or workloads with flexible start/end times, not for 24/7 production systems. **D. On-Demand for production**: While On-Demand instances provide flexibility, they are the most expensive option for 24/7 workloads. Using On-Demand for production would be cost-inefficient compared to Reserved Instances. **Key AWS cost optimization principles applied:** - Use Reserved Instances for steady-state, predictable workloads - Use On-Demand Instances for variable, intermittent workloads - Implement automation to stop unused instances to reduce costs - Match instance purchasing options to workload patterns **Additional optimization consideration**: The company could also consider using Savings Plans for production instances, which offer similar savings to Reserved Instances with more flexibility.
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A company wants to reduce the cost of its existing three-tier web architecture. The web, application, and database servers are running on Amazon EC2 instances for the development, test, and production environments. The EC2 instances average 30% CPU utilization during peak hours and 10% CPU utilization during non-peak hours.
The production EC2 instances run 24 hours a day. The development and test EC2 instances run for at least 8 hours each day. The company plans to implement automation to stop the development and test EC2 instances when they are not in use.
Which EC2 instance purchasing solution will meet the company's requirements MOST cost-effectively?
A
Use Spot Instances for the production EC2 instances. Use Reserved Instances for the development and test EC2 instances.
B
Use Reserved Instances for the production EC2 instances. Use On-Demand Instances for the development and test EC2 instances.
C
Use Spot blocks for the production EC2 instances. Use Reserved Instances for the development and test EC2 instances.
D
Use On-Demand Instances for the production EC2 instances. Use Spot blocks for the development and test EC2 instances.