SOA-C02 Cost and Performance Optimization — 25 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?

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

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

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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.. 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 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 5

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.. 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 6

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

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Reserved Instances

Answer

Compute Savings Plans

Question 7

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 8

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

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AWS Trusted Advisor

Answer

AWS CloudTrail

Question 9

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

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Reserved Instances

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Dedicated Hosts

Question 10

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 11

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

Standard Reserved Instances. Standard Reserved Instances provide significant discounts for steady-state, predictable workloads on both EC2 and RDS. Although they lock you into a specific instance family and region, you can choose Convertible Reserved Instances to retain some flexibility. Compute Savings Plans do not cover RDS databases, which are explicitly part of the workload mix, making them unsuitable. Spot Instances are not designed for steady-state workloads, and EC2 Instance Savings Plans only cover EC2 instances.

Answer

EC2 Instance Savings Plans

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Compute Savings Plans

Answer

Spot Instances

Question 12

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. 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

Question 13

A company stores video files in Amazon S3. Files are accessed frequently for the first 30 days, then weekly for the next 6 months, and then rarely after that. Files must be retained for 5 years and any access must be served within minutes. The SysOps administrator wants to minimize storage costs. Which lifecycle policy is most cost-effective?

Accepted Answer

Transition to S3 Standard-Infrequent Access after 30 days, then to S3 Glacier Instant Retrieval after 6 months.. Transition objects to S3 Standard-IA after 30 days to match the weekly access pattern at lower cost than S3 Standard. Then transition to S3 Glacier Instant Retrieval after 6 months for data that is rarely accessed but requires retrieval within milliseconds. Glacier Instant Retrieval offers the lowest storage cost among storage classes that support millisecond retrieval, making it ideal for long-term retention with the requirement that any access be served within minutes. Other classes like Glacier Deep Archive do not support expedited retrieval and have retrieval times of 12–48 hours, which fails to meet the within-minutes requirement.

Answer

Transition to S3 Standard-Infrequent Access after 30 days, then to S3 Glacier Deep Archive after 6 months.

Answer

Transition to S3 One Zone-Infrequent Access after 30 days, then to S3 Glacier after 6 months.

Answer

Transition to S3 Intelligent-Tiering after 30 days, then to S3 Glacier Flexible Retrieval after 6 months.

Question 14

A company runs a web application on Amazon EC2 instances. The application's traffic pattern is unpredictable, often spiking to 3x normal load for short periods. The SysOps administrator needs to ensure that the application can handle spikes without performance degradation while minimizing costs. Which combination of purchasing options and scaling strategies should the administrator use?

Accepted Answer

Use a mix of Reserved Instances for baseline and On-Demand for spikes, with a target tracking scaling policy.. It combines Reserved Instances for the predictable baseline load, which reduces costs through a significant discount, with On-Demand Instances to handle unpredictable spikes. The target tracking scaling policy automatically adjusts capacity based on a target metric (e.g., average CPU utilization), ensuring performance is maintained during spikes without manual intervention or over-provisioning.

Answer

Use all Spot Instances with a simple scaling policy.

Answer

Use all On-Demand Instances with a scheduled scaling policy.

Answer

Use only Reserved Instances with a manual scaling policy.

Question 15

A company runs a web application on Amazon EC2 instances that have variable traffic patterns. The application experiences steady baseline traffic with occasional spikes. The SysOps administrator wants to optimize costs while ensuring performance during spikes. Which pricing model should be used for the baseline capacity and for the burst capacity?

Accepted Answer

Reserved Instances for baseline, Spot Instances for burst capacity. Reserved Instances provide a significant discount (up to 72%) over On-Demand for steady-state workloads, making them ideal for baseline capacity. Spot Instances offer the lowest cost (up to 90% discount) but can be interrupted with a 2-minute warning, which is acceptable for burst capacity that can tolerate interruptions or be designed to failover gracefully. This combination minimizes cost while ensuring the baseline always runs and burst capacity can be added during spikes.

Answer

On-Demand Instances for baseline, Reserved Instances for burst capacity

Answer

Spot Instances for baseline, On-Demand Instances for burst capacity

Answer

Dedicated Hosts for baseline, Spot Instances for burst capacity

Question 16

A company runs a batch processing job every night on Amazon EC2 instances. The job takes exactly 2 hours to complete and can be interrupted and resumed later. The SysOps administrator wants to minimize compute costs. Which purchasing option should be used?

Accepted Answer

Spot Instances. Spot Instances are the correct choice because the batch job is fault-tolerant (can be interrupted and resumed) and runs for a fixed 2-hour window nightly. Spot Instances offer up to 90% cost savings compared to On-Demand, and with the ability to handle interruptions via checkpointing, they minimize compute costs without requiring a long-term commitment.

Answer

Reserved Instances

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On-Demand Instances

Answer

Dedicated Instances

Question 17

A SysOps administrator wants to identify underutilized Amazon EC2 instances that could be downsized to reduce costs. The administrator needs a tool that provides recommendations based on historical utilization data. Which AWS service should the administrator use?

Accepted Answer

AWS Compute Optimizer. AWS Compute Optimizer is the correct service because it analyzes historical utilization metrics (CPU, memory, network, and storage) for EC2 instances and generates specific downsizing recommendations to reduce cost without sacrificing performance. It uses machine learning to identify underutilized resources and provides actionable guidance, making it the ideal tool for this use case.

Answer

AWS Trusted Advisor

Answer

AWS Cost Explorer

Answer

AWS Budgets

Question 18

A SysOps administrator notices that an Amazon RDS DB instance is running at 10% CPU utilization consistently. The instance has 8 vCPUs and 32 GB RAM. The application's performance is adequate. Which action will reduce costs without affecting performance?

Accepted Answer

Change the DB instance to a smaller instance type.. The DB instance is over-provisioned for the current workload, as evidenced by the consistently low CPU utilization (10%) and adequate application performance. By changing to a smaller instance type, you reduce compute costs directly while maintaining sufficient capacity for the workload. This is the most straightforward cost optimization action when performance requirements are already met.

Answer

Enable Multi-AZ deployment for the DB instance.

Answer

Change the storage type from gp2 to gp3.

Answer

Increase the provisioned IOPS.

Question 19

A company runs a stateless web application on Amazon EC2 instances behind an Application Load Balancer. The application usage is consistent throughout the day and is expected to grow steadily over the next year. The SysOps administrator wants to minimize compute costs while ensuring capacity is available. Which purchasing option should the administrator use for the EC2 instances?

Accepted Answer

Reserved Instances (Standard, 1-year or 3-year). The application has a steady, predictable usage pattern and is expected to grow steadily, making Reserved Instances (Standard) the most cost-effective option. By committing to a 1-year or 3-year term, the administrator can receive a significant discount (up to 72% compared to On-Demand) while ensuring capacity is always available. This aligns with the requirement to minimize compute costs without sacrificing availability for a stateless, load-balanced workload.

Answer

On-Demand Instances

Answer

Spot Instances

Answer

Dedicated Hosts

Question 20

A company runs a batch processing application on Amazon EC2 instances. The application runs for 3 hours every night and can tolerate interruptions. The SysOps administrator needs to minimize compute costs. Which purchasing option should the administrator use?

Accepted Answer

Spot Instances. Spot Instances are ideal for this workload because the application is fault-tolerant (can tolerate interruptions) and runs on a fixed schedule (3 hours nightly). Spot Instances offer significant cost savings (up to 90% compared to On-Demand) by using spare EC2 capacity, and the batch processing can be designed to resume from checkpoints if interrupted.

Answer

On-Demand Instances

Answer

Reserved Instances

Answer

Dedicated Instances