SAA-C03 Design Cost-Optimized Architectures Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  Use Reserved Instances or Savings Plans for predictable workloads to reduce costs compared to On-Demand pricing.

  Why this is correct

  Using Reserved Instances (RIs) or Savings Plans (SPs) is a highly effective cost optimization strategy for workloads with predictable, consistent resource usage over a 1-year or 3-year term. By committing to a specific instance family, region, or compute usage, customers receive substantial discounts, often up to 72% compared to On-Demand pricing, significantly reducing the total cost of ownership for stable applications.

• ✗

  Provision additional EC2 instances to handle peak load at all times, ensuring maximum performance.

  Why it's wrong here

  Provisioning additional EC2 instances to handle peak load at all times is an inefficient and costly approach. This strategy leads to significant over-provisioning during off-peak periods, where a large portion of the allocated resources remains idle and unused. Consequently, the company incurs unnecessary expenses for compute capacity that is not actively contributing to workload performance, directly contradicting cost optimization goals.

• ✓

  Implement auto scaling to match capacity with demand, avoiding over-provisioning and reducing waste.

  Why this is correct

  Implementing Amazon EC2 Auto Scaling is a fundamental cost optimization technique that dynamically adjusts compute capacity to match actual demand. By automatically launching or terminating instances based on predefined metrics, Auto Scaling prevents both over-provisioning during low demand and under-provisioning during peak loads, ensuring optimal resource utilization and significantly reducing wasted expenditure on idle resources.

• ✓

  Use Spot Instances for fault-tolerant, flexible workloads to achieve significant cost savings.

  Why this is correct

  Leveraging Spot Instances offers the most substantial cost savings, often up to 90% compared to On-Demand prices, for fault-tolerant and flexible workloads. These instances utilize unused EC2 capacity and are suitable for batch processing, stateless applications, or development/testing environments that can tolerate interruptions, as AWS can reclaim them with a two-minute warning.

• ✗

  Store all data in Amazon S3 Standard storage class to avoid any data retrieval costs.

  Why it's wrong here

  Storing all data exclusively in Amazon S3 Standard storage class is not an optimal cost-saving strategy, as S3 Standard does incur data retrieval costs, albeit typically lower than other classes for frequent access. For data that is accessed less frequently or archived, using lifecycle policies to transition objects to S3 Infrequent Access, Glacier, or Glacier Deep Archive would yield significant storage cost reductions, despite potentially higher retrieval fees or longer retrieval times.

• ✗

  Deploy all resources in a single Availability Zone to minimize data transfer costs.

  Why it's wrong here

  Deploying all resources within a single Availability Zone (AZ) to minimize data transfer costs is a critical misstep for production workloads. While it might reduce cross-AZ data transfer charges, this approach creates a single point of failure, severely compromising the application's high availability and fault tolerance. The potential cost savings are far outweighed by the increased risk of downtime and data loss in the event of an AZ-wide outage.

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