AWS Certified Solutions Architect Professional SAP-C02 Practice Question

A mixed instances group that replaces most of the On-Demand capacity with Spot Instances yields the largest savings-Spot pricing is typically 70-90 % below On-Demand. Keeping a small On-Demand fraction ensures that some capacity launches even when Spot pools are temporarily constrained. The capacity-optimized Spot allocation strategy requests capacity from pools with the most available supply, lowering interruption frequency, and Capacity Rebalancing proactively launches replacement instances when an existing Spot Instance receives a rebalance recommendation, giving the job more time to finish. Spreading the group across at least ten instance types further improves the chance of acquiring the required vCPU count.

Using the lowest-price allocation strategy with only two instance types can select cheap but volatile pools; without Capacity Rebalancing, interruptions are more likely to delay completion. Spot blocks are no longer offered to new customers and, even when available, provide only modest discounts and no additional capacity protections. A three-year Compute Savings Plan would consume its hourly commitment 24×7, so the organization would still pay for compute during the 22.5 hours per day when the simulation is idle, making the 70 % savings target unattainable.