Explanation

The correct answer is B. Purchase a No Upfront Compute Savings Plan for a 1-year term.

Here's why:

Key Requirements:

1. Optimize cost of Amazon EC2 instances - Need cost savings
2. Change instance type and family every 2-3 months - Need flexibility

Analysis of Options:

A. Purchase Partial Upfront Reserved Instances for a 3-year term.

• ❌ Problem: Reserved Instances are tied to specific instance types, families, and Availability Zones. They don't provide the flexibility to change instance types every 2-3 months.
• ❌ Problem: 3-year term is too long for a company that needs to change configurations frequently.

B. Purchase a No Upfront Compute Savings Plan for a 1-year term.

• ✅ Advantage: Compute Savings Plans provide the highest flexibility - they apply to any instance family, size, region, OS, or tenancy within the same AWS account.
• ✅ Advantage: No upfront payment means lower initial commitment.
• ✅ Advantage: 1-year term aligns better with the requirement to change configurations every 2-3 months.
• ✅ Advantage: Provides significant cost savings (up to 66%) while maintaining flexibility.

C. Purchase All Upfront Reserved Instances for a 1-year term.

• ❌ Problem: Same limitation as option A - Reserved Instances are locked to specific instance types and families.
• ❌ Problem: All upfront payment with no flexibility to change instance types.

D. Purchase an All Upfront EC2 Instance Savings Plan for a 1-year term.

• ❌ Problem: EC2 Instance Savings Plans are more flexible than Reserved Instances but still have limitations:
  • They apply to a specific instance family (e.g., m5) and region
  • Cannot change to a different instance family (e.g., from m5 to c5)
• ❌ Problem: All upfront payment reduces flexibility.

Why Compute Savings Plan is Best:

1. Maximum Flexibility: Can switch between EC2 instance types, families, sizes, regions, OS, and tenancy
2. Cost Savings: Provides significant discounts (up to 66%) similar to Reserved Instances
3. No Instance Lock-in: Unlike Reserved Instances or EC2 Instance Savings Plans, Compute Savings Plans don't lock you into specific instance types
4. 1-year Term: Shorter commitment aligns with the frequent change requirement
5. No Upfront: Lower financial commitment and better cash flow management

Additional Considerations:

• The company's requirement to change instance types every 2-3 months suggests they might be:
  • Testing different instance types for performance optimization
  • Responding to changing workload patterns
  • Migrating applications between instance families
• Compute Savings Plans automatically apply to any eligible usage, making them ideal for dynamic environments where instance types change frequently.

Conclusion: The Compute Savings Plan with no upfront payment and 1-year term provides the optimal balance of cost savings and flexibility for a company that needs to change EC2 instance types and families every 2-3 months.