SOA-C02 Cost and Performance Optimization — 20 Questions

Question 1

A SysOps administrator manages an Amazon RDS for MySQL instance that experiences high CPU utilization during business hours. The application is read-heavy. Which action will most effectively improve performance and reduce cost?

Accepted Answer

Add a read replica.. Adding a read replica offloads read traffic from the primary RDS for MySQL instance, directly addressing the read-heavy workload and high CPU utilization. This improves performance by distributing SELECT queries to the replica, and reduces cost because you can use a smaller primary instance and only pay for the replica's resources when needed, rather than scaling up the entire instance.

Answer

Enable Multi-AZ deployment.

Answer

Scale up the instance size to a larger instance class.

Answer

Enable automated backups.

Question 2

A SysOps administrator manages a web application running on Amazon EC2 instances that run 24/7 for the next 12 months. The workload is steady and predictable. Which EC2 purchasing option provides the highest cost savings for this use case?

Accepted Answer

Standard Reserved Instances. Standard Reserved Instances provide the highest cost savings for a steady, predictable 24/7 workload over a 12-month period because they offer a significant discount (up to 72% compared to On-Demand) in exchange for a commitment to a specific instance family, region, and term length. Since the workload runs continuously without interruption, the upfront payment or partial upfront payment for a 1-year term maximizes savings without the risk of interruption or the need for flexibility.

Answer

Spot Instances

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On-Demand Instances

Answer

Savings Plans (Compute)

Question 3

A company runs a large number of EC2 instances across multiple accounts and regions. The finance team needs to track costs per project and department. Each EC2 instance must be tagged with a ProjectID and Department tag. A SysOps administrator needs to ensure that all newly launched EC2 instances are tagged automatically before they can be used, and that existing untagged instances are retroactively tagged. The tags must be propagated to cost reports in AWS Cost Explorer. Which combination of steps will achieve this with the least operational overhead?

Accepted Answer

Use AWS Config with auto-remediation to tag new instances, and activate the tags as cost allocation tags. For existing instances, run the Tag Editor with a CSV import.. Option A is correct because AWS Config with auto-remediation can automatically tag newly launched EC2 instances using a custom Lambda function or SSM document triggered by a Config rule (e.g., 'required-tags'), ensuring compliance before instances are used. Activating the tags as cost allocation tags in AWS Cost Explorer allows the tags to appear in cost reports. For existing untagged instances, the Tag Editor with a CSV import provides a bulk, low-overhead method to retroactively apply tags across accounts and regions.

Answer

Create an AWS Lambda function that tags instances at launch via CloudTrail events, and use AWS Budgets to enforce tagging.

Answer

Use AWS Cost Categories to automatically group costs based on resource tags.

Answer

Ensure all AMIs used have tags that propagate to instances, and enable cost allocation tags.

Question 4

A company runs a batch processing application on Amazon EC2 that runs for 2 hours every night. The workload can tolerate interruptions. Which EC2 purchasing option provides the lowest cost for this use case?

Accepted Answer

Spot Instances. Spot Instances are the correct choice because the workload is fault-tolerant, runs for a fixed 2-hour window nightly, and can tolerate interruptions. Spot Instances offer significant cost savings (up to 90% off On-Demand) by using spare EC2 capacity, which aligns perfectly with a batch job that can be retried if interrupted.

Answer

On-Demand Instances

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Reserved Instances

Answer

Dedicated Hosts

Question 5

A company runs a web application on Amazon EC2 instances behind an Application Load Balancer (ALB). The application reads data from an Amazon RDS for MySQL database. During peak hours, the database CPU utilization is consistently high, and the application experiences increased latency. The SysOps administrator observes that 90% of database queries are read-only. Which combination of actions will both improve performance and optimize costs?

Accepted Answer

Implement a read replica for the RDS instance and modify the application to route read queries to the read replica. Option B is correct because implementing a read replica offloads read-heavy (90%) queries from the primary RDS instance, reducing CPU utilization and latency. Modifying the application to route read queries to the replica distributes the workload, improving performance while avoiding costly vertical scaling. This optimizes costs by using a smaller primary instance and paying only for the replica's resources.

Answer

Enable Multi-AZ for the RDS instance and scale up the instance size

Answer

Enable Amazon RDS Performance Insights and increase the storage allocation

Answer

Implement Amazon ElastiCache for Memcached in front of the database and migrate read-heavy queries to cache

Question 6

A company runs a web application on Amazon EC2 instances that are part of an Auto Scaling group. The application's traffic is predictable with regular peaks during business hours and low traffic at night. The SysOps administrator wants to optimize costs while ensuring that performance meets demand. The administrator also needs to minimize manual intervention. Which scaling policy should be used?

Accepted Answer

Scheduled scaling. Scheduled scaling is the correct choice because the traffic pattern is predictable with regular peaks during business hours and low traffic at night. This policy allows the administrator to define specific times to increase or decrease the desired capacity of the Auto Scaling group, matching capacity to demand without manual intervention and optimizing costs by reducing instances during off-peak hours.

Answer

Target tracking scaling

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Simple scaling

Answer

Manual scaling

Question 7

A company stores large volumes of log data in Amazon S3. The logs are accessed frequently for the first 30 days, then occasionally for the next 60 days, and after 90 days they are rarely accessed but must be retained for 7 years for compliance. The SysOps administrator wants to minimize storage costs while ensuring data is available when needed. Which S3 lifecycle policy configuration should be applied?

Accepted Answer

Transition objects to S3 Standard-IA after 30 days, and to S3 Glacier Deep Archive after 90 days. Delete after 7 years.. Option D is correct because it aligns the lifecycle transitions with the access patterns: frequent access for the first 30 days (S3 Standard), occasional access for the next 60 days (S3 Standard-IA), and rare access after 90 days (S3 Glacier Deep Archive, the lowest-cost storage class for long-term retention). The deletion after 7 years meets compliance requirements while minimizing costs by using progressively cheaper storage classes.

Answer

Transition objects to S3 Standard-IA after 30 days, and to S3 Glacier after 60 days. Delete after 7 years.

Answer

Transition objects to S3 Glacier Deep Archive after 30 days, and delete after 7 years.

Answer

Transition objects to S3 One Zone-IA after 30 days, and to S3 Glacier Deep Archive after 90 days. Delete after 7 years.

Question 8

A company runs a read-heavy database workload on Amazon RDS for PostgreSQL with a primary instance and two read replicas. The SysOps administrator observes that the read replicas frequently experience high replica lag during peak hours, causing stale reads for the application. The administrator needs to reduce replica lag while optimizing costs. The workload is predictable, with spikes during business hours and low traffic at night. Which combination of actions should the administrator take?

Accepted Answer

Upgrade the instance class of the read replicas to a larger type with more CPU and memory to handle the increased WAL replay rate.. Option B is correct because upgrading the read replica instance class provides more CPU and memory, which directly increases the WAL replay rate. In RDS for PostgreSQL, replica lag is primarily caused by the replica's inability to apply WAL changes as fast as the primary generates them. A larger instance class alleviates this bottleneck without incurring the cost of upgrading the primary instance.

Answer

Convert the read replicas to Multi-AZ instances to improve the replication process and reduce lag.

Answer

Add additional read replicas to distribute the read load and reduce the lag on each individual replica.

Answer

Upgrade the primary DB instance to a larger class with increased IOPS to reduce the amount of data that needs to be replicated.

Question 9

A company runs a mix of Amazon EC2 instances and AWS Fargate tasks that are used for both production and development workloads. The usage is steady and predictable. The SysOps administrator wants to maximize cost savings across both compute services without having to manage specific instances or sizes. Which purchasing option should the administrator recommend?

Accepted Answer

Purchase Compute Savings Plans for a 1-year or 3-year term with a commitment that covers the expected compute spend.. Compute Savings Plans offer the most flexibility, automatically applying to EC2 instances (regardless of instance family, size, or region) and Fargate tasks. Since the company has a mix of both services and wants to maximize savings without managing specific instances or sizes, a 1-year or 3-term Compute Savings Plan with a commitment matching expected spend provides up to 66% savings while covering all compute usage. This aligns with the steady and predictable workload described.

Answer

Purchase EC2 Instance Savings Plans for the most commonly used instance family and region.

Answer

Purchase Standard Reserved Instances for the EC2 instances and convert Fargate tasks to use Spot Instances.

Answer

Use On-Demand instances for both EC2 and Fargate because the administrator does not want to make a commitment.

Question 10

A company runs a web application on Amazon EC2 instances in an Auto Scaling group. The application experiences steady traffic during business hours and very low traffic overnight. The SysOps administrator wants to optimize costs by using a mix of On-Demand and Spot Instances. The administrator also requires that the total capacity never falls below the baseline level needed during business hours, even if Spot Instances are reclaimed. Which combination of Auto Scaling features should be used?

Accepted Answer

Use a mixed instances policy and set the 'On-Demand Base' capacity to the minimum number of instances required during business hours, and 'On-Demand percentage above base' to 0% so that any additional capacity is Spot.. Option A is correct because a mixed instances policy allows the Auto Scaling group to use both On-Demand and Spot Instances. By setting the 'On-Demand Base' capacity to the minimum number of instances required during business hours, you guarantee that baseline capacity is always fulfilled by On-Demand Instances, which are not subject to interruption. Setting 'On-Demand percentage above base' to 0% ensures that any additional capacity beyond the base is fulfilled by Spot Instances, optimizing cost while maintaining the required capacity floor.

Answer

Use a launch template that specifies a Spot Instance type and set the total capacity to the desired level, relying on capacity rebalance to replace interrupted Spot Instances.

Answer

Purchase Compute Savings Plans to cover the entire Auto Scaling group, and use only Spot Instances for all capacity.

Answer

Configure the Auto Scaling group with a launch template that sets the instance market to 'spot' and use a scaling policy that always maintains the minimum capacity.

Question 11

A company runs a batch processing job on Amazon EC2 that runs for 2 hours every night. The job can tolerate interruptions and can resume from the last checkpoint. The SysOps administrator needs to minimize compute costs. Which EC2 purchasing option should be used?

Accepted Answer

Spot Instances. Spot Instances are ideal for fault-tolerant, interruptible workloads like this batch processing job because they offer significant cost savings (up to 90% off On-Demand prices) in exchange for being reclaimable by AWS with a 2-minute warning. Since the job can resume from the last checkpoint, interruptions do not cause data loss or restart from scratch, making Spot Instances the most cost-effective choice.

Answer

On-Demand Instances

Answer

Reserved Instances

Answer

Compute Savings Plans

Question 12

A SysOps administrator wants to identify Amazon EC2 instances that are underutilized to reduce costs. The administrator needs recommendations for rightsizing instances based on historical CPU and memory usage. Which AWS service provides these recommendations?

Accepted Answer

AWS Compute Optimizer. AWS Compute Optimizer is the correct service because it analyzes historical utilization metrics (CPU, memory, I/O, and network throughput) from Amazon CloudWatch and generates rightsizing recommendations for EC2 instances. It uses machine learning to identify underutilized instances and suggests instance types that better match workload requirements, directly addressing the need to reduce costs through rightsizing.

Answer

AWS Cost Explorer

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AWS Trusted Advisor

Answer

AWS CloudTrail

Question 13

A company wants to receive an alert when its AWS spending exceeds $5,000 in a month. The SysOps administrator needs to set up a proactive alert that monitors actual costs. Which AWS service should be used?

Accepted Answer

AWS Budgets. AWS Budgets is the correct service because it allows you to set a cost budget that proactively sends alerts when actual costs exceed a specified threshold (e.g., $5,000 per month). Unlike Cost Explorer, which is an analytical tool, Budgets provides real-time notifications via Amazon SNS when costs reach or are forecasted to exceed the budgeted amount, enabling proactive monitoring of actual spending.

Answer

AWS Cost Explorer

Answer

AWS Trusted Advisor

Answer

AWS CloudTrail

Question 14

A company uses Amazon S3 to serve large files to users. The files are accessed frequently for the first 30 days after upload, then access drops significantly. The SysOps administrator wants to minimize storage costs while ensuring low-latency access for frequently accessed files and automatic optimization for changing access patterns. Which S3 storage class configuration should be used?

Accepted Answer

Use S3 Intelligent-Tiering.. S3 Intelligent-Tiering is the correct choice because it automatically moves objects between three access tiers (frequent, infrequent, and archive instant) based on changing access patterns, without any lifecycle rules or performance impact. This meets the requirement for low-latency access for frequently accessed files and automatic optimization, while minimizing storage costs as access drops after 30 days.

Answer

Use S3 Standard for 30 days, then transition to S3 Glacier Deep Archive.

Answer

Use S3 Standard then transition to S3 Glacier Flexible Retrieval after 30 days.

Answer

Use S3 One Zone-IA for the first 30 days, then transition to S3 Standard-IA.

Question 15

A company runs a batch processing job on Amazon EC2 instances that runs for 3 hours each night. The job can be interrupted and can resume from the last checkpoint without data loss. The SysOps administrator wants to minimize compute costs for this workload. Which Amazon EC2 purchasing option should be used?

Accepted Answer

Spot Instances. Spot Instances are correct because the batch job is fault-tolerant (can be interrupted and resume from checkpoints) and runs for a fixed 3-hour window nightly. Spot Instances offer significant cost savings (up to 90% off On-Demand) by using spare EC2 capacity, which can be reclaimed by AWS with a 2-minute interruption notice. Since the workload can handle interruptions gracefully, Spot Instances minimize compute costs while meeting the job's requirements.

Answer

On-Demand Instances

Answer

Reserved Instances

Answer

Dedicated Hosts

Question 16

A company uses Amazon S3 to store large files that are frequently accessed for the first 30 days after upload. After 30 days, access frequency drops significantly but users still need retrieval within minutes. The SysOps administrator wants to minimize storage costs while ensuring low-latency access for frequently accessed files and automatic optimization for changing access patterns. Which S3 storage class configuration should the company use?

Accepted Answer

Use S3 Intelligent-Tiering. B is correct because S3 Intelligent-Tiering automatically moves objects between two access tiers (frequent and infrequent access) based on changing access patterns, with no retrieval fees and low-latency access. This matches the requirement of frequent access for the first 30 days, then infrequent access with minutes-later retrieval, while minimizing storage costs without manual intervention.

Answer

Use S3 Standard for all objects, and manually move older objects to S3 Standard-IA after 30 days.

Answer

Use S3 Standard-IA for all objects, and accept higher retrieval costs for the first 30 days.

Answer

Use S3 Glacier Instant Retrieval

Question 17

A SysOps administrator manages a fleet of Amazon EC2 instances. The administrator needs to identify underutilized instances and receive recommendations for instance type changes to reduce costs. Which AWS service should be used to provide these rightsizing recommendations?

Accepted Answer

AWS Compute Optimizer. AWS Compute Optimizer is the correct service because it uses machine learning to analyze historical utilization metrics (CPU, memory, network, and storage) of EC2 instances and generates rightsizing recommendations, including instance type changes, to reduce costs and improve performance. It directly addresses the need to identify underutilized instances and provide actionable recommendations for cost optimization.

Answer

AWS Cost Explorer

Answer

AWS Trusted Advisor

Answer

Amazon CloudWatch Dashboard

Question 18

A company stores video files in Amazon S3. The files are accessed frequently for the first week, then weekly for the next month, and then rarely after that. The files must be retained for 5 years and any access must be served within minutes. The SysOps administrator needs to minimize storage costs while meeting these requirements. Which lifecycle policy configuration is the most cost-effective?

Accepted Answer

Transition to S3 Standard-IA after 7 days, then to S3 Glacier Instant Retrieval after 30 days.. Option C is correct because it transitions to S3 Standard-IA after 7 days (matching the frequent first-week access), then to S3 Glacier Instant Retrieval after 30 days (matching the weekly access for the next month). Glacier Instant Retrieval provides millisecond retrieval for rarely accessed data, meeting the 'within minutes' requirement while minimizing costs compared to Standard-IA or Intelligent-Tiering.

Answer

Transition to S3 Standard-IA after 7 days, then to S3 Glacier Flexible Retrieval after 30 days.

Answer

Transition to S3 One Zone-IA after 7 days, then to S3 Glacier Deep Archive after 30 days.

Answer

Transition to S3 Intelligent-Tiering after 7 days.

Question 19

A company runs a mix of Amazon EC2 instances, Amazon RDS databases, and AWS Lambda functions for production workloads. The workloads are steady-state and predictable. The SysOps administrator wants to reduce costs while maintaining flexibility to change instance families and regions. Which pricing model should be recommended?

Accepted Answer

Compute Savings Plans. Compute Savings Plans provide the most flexibility because they automatically apply to EC2 instances, AWS Lambda, and AWS Fargate usage across any instance family, size, or region, as long as the compute spend stays within the committed hourly amount. This matches the requirement to reduce costs on steady-state workloads while retaining the ability to change instance families and regions, unlike EC2 Instance Savings Plans which are limited to a specific instance family in a region.

Answer

EC2 Instance Savings Plans

Answer

Standard Reserved Instances

Answer

Spot Instances

Question 20

A company stores application logs in Amazon S3. The logs are rarely accessed after the first 30 days, but must be retained for 7 years for compliance. The SysOps administrator wants to minimize storage costs while ensuring logs are available for retrieval within 12 hours if needed. Which S3 lifecycle configuration is the most cost-effective?

Accepted Answer

S3 Standard for 30 days, then transition to S3 Glacier Deep Archive. Option A is correct because it transitions logs from S3 Standard (for frequent access during the first 30 days) to S3 Glacier Deep Archive, which offers the lowest storage cost for long-term retention. Since logs must be retained for 7 years and only need retrieval within 12 hours, Glacier Deep Archive's 12-hour standard retrieval time meets the requirement while minimizing costs.

Answer

S3 Standard for 30 days, then transition to S3 Glacier (Flexible Retrieval)

Answer

Use S3 Intelligent-Tiering from the start

Answer

S3 Standard for 30 days, then transition to S3 One Zone-IA