SOA-C02 Cost and Performance Optimization Practice Test 3 — 15 Questions

Question 1

A company runs a batch processing application on Amazon EC2 instances that runs every night for 2 hours. The job can be interrupted and resumed without any issue. The SysOps administrator wants to minimize compute costs for this workload. Which EC2 purchasing option should be used?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Spot Instances. Spot Instances are the correct choice because the workload is fault-tolerant (can be interrupted and resumed) and runs for only 2 hours nightly. Spot Instances offer significant cost savings (up to 90% off On-Demand) but can be reclaimed by AWS with a 2-minute warning, which is acceptable here since the job can resume without issue. This aligns with the goal of minimizing compute costs for a non-critical, interruptible batch process.

Answer

On-Demand Instances

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Reserved Instances

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Dedicated Hosts

Question 2

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

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Dedicated Hosts

Question 3

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.

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Create a global table to distribute write traffic.

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Use Amazon ElastiCache to buffer write requests.

Question 4

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 5

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.. 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.

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Use S3 Intelligent-Tiering.

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

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.. 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.

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

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Disable health checks to avoid instance replacement.

Question 7

Match each AWS security service to its purpose.

Accepted Answer

AWS WAF: A web application firewall that helps protect web applications from common web exploits. These services are core to AWS security. AWS WAF protects web applications from exploits, AWS Shield protects against DDoS attacks, AWS IAM manages user access and permissions, and AWS KMS manages encryption keys. Common confusions include mixing WAF and Shield (both are protective but for different threats) and IAM with KMS (IAM for access, KMS for encryption).

Answer

AWS WAF: A managed Distributed Denial of Service (DDoS) protection service that safeguards applications running on AWS

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AWS IAM: A managed service that makes it easy to create and control the encryption keys used to encrypt your data

Question 8

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.

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Amazon CloudWatch

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Elastic Load Balancing

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AWS Lambda

Question 9

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.. 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.

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Create a read replica and promote it when needed.

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Purchase a reserved instance for the DB instance.

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

Question 10

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.. Both Spot Instances and Scheduled Reserved Instances provide cost reduction opportunities for EC2 environments. Spot Instances offer up to 90% discount compared to On-Demand and are specifically designed for interruptible, non-critical workloads like batch jobs. Scheduled Reserved Instances provide a capacity reservation and a discount over On-Demand for workloads that run on a predictable, recurring schedule, making them a valid cost-saving option for batch jobs that are scheduled at fixed times. Associating Elastic IP addresses, using Dedicated Hosts, or using On-Demand Instances do not reduce costs.

Answer

Associate Elastic IP addresses with the instances.

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Use Dedicated Hosts.

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Use On-Demand Instances.

Question 11

Which THREE AWS services can be used to monitor and optimize costs? (Choose THREE.)

Accepted Answer

AWS Trusted Advisor. AWS Trusted Advisor provides cost optimization recommendations by analyzing your AWS environment and identifying idle resources, underutilized instances, and reserved instance opportunities. It offers specific checks like 'Low Utilization Amazon EC2 Instances' and 'Idle Load Balancers' that directly help reduce spending.

Answer

AWS Shield

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AWS CloudFormation

Question 12

Which TWO configurations can improve the performance of an Amazon RDS for PostgreSQL database that is experiencing high read latency? (Choose TWO.)

Accepted Answer

Enable provisioned IOPS on the DB instance.. Enabling Provisioned IOPS on an Amazon RDS for PostgreSQL database provides consistent and predictable I/O performance, which directly reduces read latency by ensuring sufficient IOPS for read-intensive workloads. Option C is correct because creating a read replica offloads read traffic from the primary DB instance to the replica, reducing contention and improving read latency for the primary instance.

Answer

Upgrade to a larger instance size.

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Enable Multi-AZ deployment.

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Enable storage auto-scaling.

Question 13

A SysOps administrator notices that an EC2 instance's CPU utilization is consistently above 90% during peak hours. Which action will improve performance without over-provisioning resources?

Accepted Answer

Change the instance type to a larger size, such as moving from t3.medium to t3.large.. Changing the instance type to a larger size (e.g., from t3.medium to t3.large) vertically scales the instance, providing more vCPUs and memory to handle the increased CPU load during peak hours. This directly addresses the high CPU utilization without over-provisioning, as you are only scaling up the specific resource that is constrained. Spot Instances (A) do not improve performance; they offer lower cost but same performance. Increasing EBS volumes (B) does not affect CPU performance. Auto Scaling (D) adds more instances (horizontal scaling), which can over-provision if the single instance's capacity is sufficient after a vertical scale-up.

Answer

Use Spot Instances instead of On-Demand.

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Increase the number of EBS volumes attached to the instance.

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Configure Auto Scaling to add more instances during peak hours.

Question 14

A SysOps administrator needs to reduce costs for a fleet of EC2 instances that run a stateless web application. The instances are currently On-Demand. The workload runs 24/7 for the next 12 months. Which pricing model provides the greatest cost savings?

Accepted Answer

Purchase Standard Reserved Instances for a 1-year term.. Standard Reserved Instances (RIs) for a 1-year term provide a significant discount (up to 40%) over On-Demand pricing for workloads that run continuously 24/7. Since this stateless web application runs constantly for the next 12 months, Standard RIs offer the greatest cost savings among the options, as they are designed for steady-state usage and do not require flexibility in instance family or operating system.

Answer

Use Dedicated Hosts.

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Use Spot Instances.

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Purchase Convertible Reserved Instances for a 1-year term.

Question 15

Which THREE AWS features can be used to improve the performance of an Amazon DynamoDB table that is experiencing high read latency? (Choose THREE.)

Accepted Answer

Enable DynamoDB Accelerator (DAX).. DynamoDB Accelerator (DAX) is a fully managed, highly available, in-memory cache that can reduce DynamoDB response times from milliseconds to microseconds. By caching frequently read items, DAX offloads read requests from the underlying table, directly addressing high read latency without requiring additional read capacity units or table modifications.

Answer

Enable Auto Scaling for read capacity.

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Use Time to Live (TTL) to delete old items.