SOA-C02 Cost and Performance Optimization Practice Test 4 — 15 Questions

Question 1

A company runs a batch processing job every Saturday for 3 hours. The job can be interrupted and resumed at any point. The SysOps administrator wants to minimize compute costs for this workload. Which EC2 purchasing option should the administrator use?

Accepted Answer

Spot Instances. Spot Instances are ideal for fault-tolerant, interruptible workloads like batch processing that can be resumed. They offer significant cost savings (up to 90% compared to On-Demand) because they use spare EC2 capacity, which can be reclaimed by AWS with a 2-minute interruption notice. Since the job runs only 3 hours weekly and can be interrupted and resumed, Spot Instances minimize compute costs effectively.

Answer

On-Demand Instances

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Reserved Instances

Answer

Dedicated Hosts

Question 2

A company uses an Amazon DynamoDB table with on-demand capacity mode. The table handles a workload with a steady baseline of 500 writes per second but spikes to 2,000 writes per second for a few hours each day. The SysOps administrator wants to reduce costs without affecting application performance during spikes. Which action should the administrator take?

Accepted Answer

Switch to provisioned capacity with auto scaling to handle the spikes.. On-demand capacity mode is ideal for unpredictable workloads but costs more per write than provisioned capacity. Since this workload has a predictable baseline and spikes, switching to provisioned capacity with auto scaling allows you to pay a lower rate for the steady 500 writes per second while auto scaling automatically adds capacity to handle the 2,000 writes per second spikes, reducing overall cost without impacting performance.

Answer

Enable DynamoDB Accelerator (DAX) to cache reads.

Answer

Create a global table to distribute write traffic.

Answer

Use Amazon ElastiCache to buffer write requests.

Question 3

A company uses multiple AWS accounts and needs to generate a detailed cost and usage report that can be queried using Amazon Athena for custom analysis. Which AWS service should the administrator enable?

Accepted Answer

AWS Cost and Usage Reports. AWS Cost and Usage Reports (CUR) is the correct service because it generates detailed cost and usage data in CSV or Parquet format, which can be directly queried using Amazon Athena via integration with AWS Glue and Amazon QuickSight. This enables custom analysis and ad-hoc queries on the full billing dataset, unlike other services that provide pre-aggregated views or alerts.

Answer

AWS Cost Explorer

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AWS Budgets

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AWS Application Cost Profiler

Question 4

A SysOps administrator notices that some Amazon S3 objects have not been accessed for over 90 days and need to be retained for compliance purposes. The administrator wants to reduce storage costs by moving these objects to the lowest-cost storage class. Which action should the administrator take?

Accepted Answer

Create an S3 lifecycle rule to transition objects older than 90 days to S3 Glacier Deep Archive.. Option B is correct because S3 Glacier Deep Archive is the lowest-cost storage class in Amazon S3, designed for long-term retention of data that is accessed infrequently. An S3 lifecycle rule can automatically transition objects older than 90 days to this class, reducing costs without manual intervention. This meets the compliance requirement to retain the objects while optimizing storage expenditure.

Answer

Manually move the objects to S3 One Zone-IA.

Answer

Use S3 Intelligent-Tiering.

Answer

Enable S3 Versioning and create a lifecycle rule to delete old versions.

Question 5

A company runs a web application on a fleet of Amazon EC2 instances behind an Application Load Balancer. The application has predictable traffic patterns with high traffic during business hours and low traffic at night. The SysOps administrator wants to reduce compute costs while ensuring the application remains responsive during peak hours. The administrator has already implemented Auto Scaling based on CPU utilization. Which additional action should the administrator take to optimize costs?

Accepted Answer

Purchase Reserved Instances for the baseline capacity and use Spot Instances for the additional capacity during peak hours. Option B is correct because it combines Reserved Instances for predictable baseline capacity (lower cost per hour) with Spot Instances for elastic peak demand, leveraging Auto Scaling to handle variable traffic. This hybrid approach reduces compute costs compared to using On-Demand instances for all capacity, while maintaining responsiveness during peak hours.

Answer

Use On-Demand instances only

Answer

Increase the minimum number of instances in the Auto Scaling group

Answer

Use Dedicated Hosts to reduce licensing costs

Question 6

An EC2 Auto Scaling group runs a stateless web application with predictable daily peaks. Which two actions can reduce cost while preserving capacity during peak periods? (Choose 2.)

Accepted Answer

Configure scheduled scaling actions for the known peak window.. Option A is correct because scheduled scaling allows you to proactively increase capacity before the predictable daily peak and reduce it afterward, ensuring you only pay for the resources needed during the peak window. This avoids over-provisioning for the entire day, directly reducing costs while maintaining performance during high-demand periods.

Answer

Run all instances as On-Demand at maximum peak size all day.

Answer

Disable health checks to avoid instance replacement.

Question 7

An application runs on c5.xlarge EC2 instances 24 hours a day, 7 days a week in us-east-1. The workload is stable and will not change instance type for at least 12 months. The team wants to reduce compute costs by 30 to 40 percent compared to On-Demand pricing. Which purchasing option achieves this with the lowest financial risk?

Accepted Answer

Purchase a 1-year Standard Reserved Instance for c5.xlarge in us-east-1 with All Upfront or Partial Upfront payment. A 1-year Standard Reserved Instance (RI) with All Upfront or Partial Upfront payment offers a 30-40% discount over On-Demand pricing for a stable, always-on workload. This option provides the lowest financial risk because it commits to a fixed instance type and region for only one year, matching the workload's stable nature without the flexibility premium of Convertible RIs or the interruption risk of Spot Instances.

Answer

Use Spot Instances with an interruption tolerance of 5 minutes for the workload

Answer

Enable EC2 Auto Scaling with a target tracking policy to scale down to zero instances during off-peak hours

Answer

Purchase a 3-year Convertible Reserved Instance to maximize the discount percentage

Question 8

A media company stores millions of video files in S3. Some files are accessed heavily after upload (when new) and rarely afterward; others are accessed unpredictably across months. The team cannot predict which files will be accessed and when. They want to minimize storage costs without risking retrieval latency penalties or per-object retrieval fees. Which storage class is appropriate?

Accepted Answer

Use S3 Intelligent-Tiering so objects automatically move between Frequent and Infrequent Access tiers based on access patterns, with no retrieval fees. S3 Intelligent-Tiering is the correct choice because it automatically moves objects between Frequent Access and Infrequent Access tiers based on changing access patterns, with no retrieval fees and no performance impact (millisecond latency). This matches the unpredictable access pattern described, as the service monitors access at the object level and adjusts storage tier without manual lifecycle rules or retrieval costs.

Answer

Use S3 Standard-IA and configure a lifecycle policy to move objects back to Standard after every access

Answer

Use S3 Glacier Instant Retrieval for all objects because it offers the lowest storage cost with millisecond retrieval

Answer

Use S3 Standard for all objects because it has no retrieval fees and provides the best availability

Question 9

The finance team was surprised by a $12,000 spike in EC2 costs last month caused by a runaway Auto Scaling group. They want to receive an email alert within hours whenever any AWS service cost behaves unexpectedly, without manually setting fixed dollar thresholds for each service. Which AWS cost management feature provides this?

Accepted Answer

Enable Cost Anomaly Detection with an AWS services monitor and create an alert subscription to email the finance team when an anomaly is detected. Cost Anomaly Detection uses machine learning to model historical spending patterns for each AWS service and automatically detects unusual spikes without requiring manual thresholds. By creating an AWS services monitor and linking an alert subscription, the finance team receives email notifications within hours when any service deviates from its expected cost behavior, directly addressing the need for service-agnostic, threshold-free alerts.

Answer

Create an AWS Budget with a monthly EC2 cost threshold of $10,000 and an alert at 80 percent of the threshold

Answer

Enable AWS Cost Explorer and review the daily cost breakdown each morning to spot unexpected charges

Answer

Configure CloudWatch Billing alarms with a static threshold for each AWS service individually

Question 10

Drag and drop the steps to configure a VPC peering connection between two VPCs into the correct order.

Question 11

Match each AWS security service to its purpose.

Question 12

A company runs a web application on EC2 instances behind an Application Load Balancer. The application experiences unpredictable traffic spikes. Which AWS service should be used to automatically adjust the number of EC2 instances based on demand, optimizing cost and performance?

Accepted Answer

AWS Auto Scaling. AWS Auto Scaling is the correct service because it automatically adjusts the number of EC2 instances in response to demand, using scaling policies based on metrics like CPU utilization or request count. This ensures that the application can handle traffic spikes without manual intervention, optimizing both cost (by scaling down during low demand) and performance (by scaling up during spikes). The service integrates directly with the Application Load Balancer to register and deregister instances as needed.

Answer

Amazon CloudWatch

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Elastic Load Balancing

Answer

AWS Lambda

Question 13

A SysOps administrator needs to reduce costs for an Amazon RDS for MySQL DB instance that is used for development. The instance is only needed during business hours (9 AM to 5 PM) on weekdays. Which solution is the MOST cost-effective while maintaining the ability to start and stop the instance on a schedule?

Accepted Answer

Use AWS Instance Scheduler to stop and start the RDS instance on a schedule.. Option D is correct because AWS Instance Scheduler is a fully managed solution designed specifically to start and stop RDS instances on a defined schedule, such as weekdays from 9 AM to 5 PM. This eliminates compute costs during non-business hours while preserving the instance's storage and configuration, making it the most cost-effective and reliable approach for a development environment.

Answer

Create a read replica and promote it when needed.

Answer

Purchase a reserved instance for the DB instance.

Answer

Use a Lambda function to stop the instance at 5 PM and start it at 9 AM on weekdays.

Question 14

A company is using Amazon S3 to store historical data. The data is accessed frequently for the first 30 days, then accessed infrequently for the next 90 days, and after 120 days it is rarely accessed but must be retained for 7 years for compliance. Which S3 lifecycle policy provides the LOWEST cost while meeting these requirements?

Accepted Answer

Standard for 30 days, then transition to Standard-IA for 90 days, then to Glacier Deep Archive.. Option A is correct because it aligns the storage class transitions precisely with the access patterns: Standard for frequent access (first 30 days), Standard-IA for infrequent access (next 90 days), and Glacier Deep Archive for long-term retention (after 120 days). This minimizes cost by avoiding paying for premium storage when data is rarely accessed, while still meeting the 7-year compliance requirement at the lowest possible storage cost.

Answer

Standard for 30 days, then transition to One Zone-IA for 90 days, then to Glacier Deep Archive.

Answer

Standard for 120 days, then transition to Glacier Deep Archive.

Answer

Standard for 30 days, then transition to Glacier for the remaining life.

Question 15

Which TWO actions can reduce costs for an Amazon EC2 environment that runs non-critical batch jobs that can be interrupted? (Choose TWO.)

Accepted Answer

Use Scheduled Reserved Instances.. Scheduled Reserved Instances allow you to reserve capacity for recurring time windows, such as daily or weekly batch jobs. This provides a significant discount over On-Demand pricing (up to 30-40%) while ensuring capacity is available when needed, making it cost-effective for predictable, interruptible workloads.

Answer

Associate Elastic IP addresses with the instances.

Answer

Use Dedicated Hosts.

Answer

Use On-Demand Instances.