SOA-C02 Cost and Performance Optimization Practice Test 2 — 15 Questions

Question 1

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?

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 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.

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Reserved Instances

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On-Demand Instances

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Dedicated Instances

Question 2

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.

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AWS Trusted Advisor

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AWS Cost Explorer

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AWS Budgets

Question 3

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.

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Change the storage type from gp2 to gp3.

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Increase the provisioned IOPS.

Question 4

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.

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On-Demand Instances

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Spot Instances

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Dedicated Hosts

Question 5

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.

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On-Demand Instances

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Reserved Instances

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Dedicated Instances

Question 6

A company runs a web application on Amazon EC2 instances that run 24/7. The application has a predictable and steady load. The SysOps administrator wants to minimize compute costs while ensuring the required capacity is always available. Which purchasing option should be used?

Accepted Answer

Reserved Instances. Reserved Instances (RIs) are the correct choice because the workload runs 24/7 with a predictable and steady load. By committing to a 1- or 3-year term, the company can achieve a significant discount (up to 72%) compared to On-Demand pricing, while ensuring capacity is always available. This aligns with the goal of minimizing compute costs without sacrificing availability.

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On-Demand Instances

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Spot Instances

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Dedicated Hosts

Question 7

A company runs a CPU-intensive batch processing job daily on a single Amazon EC2 instance. The job requires high compute performance but uses minimal memory. The instance is typically idle for the rest of the day. The SysOps administrator needs to minimize costs while ensuring the job completes within a 1-hour window. Which purchasing option and instance family should the administrator use?

Accepted Answer

Reserved Instance (1-year, all upfront) with a compute-optimized (C-family) instance. A Reserved Instance with a compute-optimized (C-family) instance is the appropriate choice because the job requires high CPU performance and must complete reliably within a 1-hour window. Spot Instances are subject to interruption and cannot guarantee completion, especially for a single-instance batch job. While Reserved Instances involve a 1-year commitment, this option ensures the instance is available when needed, and the compute-optimized family matches the CPU-intensive profile. On-Demand instances would be cheaper for low utilization, but that option is not available with a compute-optimized family in the given choices.

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On-Demand Instance with a general-purpose (T-family) instance

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Spot Instance with a compute-optimized (C-family) instance

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On-Demand Instance with a memory-optimized (R-family) instance

Question 8

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?

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

Accepted Answer

Reserved Instances (Standard). A Standard Reserved Instance is the best choice because the job runs every night for exactly 2 hours with predictable resource requirements, making it ideal for a 1-year or 3-year commitment that provides a significant discount (up to 72%) over On-Demand pricing. Since the job cannot tolerate interruptions, Reserved Instances offer capacity reservation and cost savings without the risk of termination that Spot Instances carry.

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Spot Instances

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On-Demand Instances

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Dedicated Hosts

Question 9

A company runs a web application on a fleet of Amazon EC2 instances. The application uses Amazon EBS volumes of type gp2 (General Purpose SSD). Each volume is 100 GB, which provides a baseline of 3000 IOPS (the minimum performance of gp2). The SysOps administrator monitors the volumes and finds that the average IOPS used is only 1,500, and the application performance is adequate. The administrator wants to reduce storage costs without affecting performance. Which action should the administrator take?

Accepted Answer

Migrate the volumes from gp2 to gp3 and provision the baseline IOPS to match the actual usage.. Migrating from gp2 to gp3 is the correct action because gp3 has a lower per-GB cost while providing a baseline of 3,000 IOPS and 125 MB/s. For a 100 GB gp2 volume, the baseline is only 300 IOPS (3 IOPS/GB), so the observed usage of 1,500 IOPS would actually exceed that baseline and rely on burst credits. Migrating to gp3 guarantees a 3,000 IOPS baseline, which removes the need for burst credits and reduces cost. Note that gp3 IOPS cannot be set below 3,000; the cost benefit comes from the lower per-GB price, not from provisioning lower IOPS.

Answer

Replace the EBS volumes with instance store volumes.

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Change the volume type to io2 (Provisioned IOPS SSD) and reduce the provisioned IOPS.

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Change the volume type to Cold HDD (sc1) to reduce cost.

Question 10

A company runs a web application on a fleet of Amazon EC2 instances that operate 24/7 with a steady and predictable load. The SysOps administrator wants to minimize compute costs while ensuring the required capacity is always available. Which EC2 purchasing option should the administrator use?

Accepted Answer

Reserved Instances. Reserved Instances (RIs) are the correct choice because the workload runs 24/7 with steady, predictable load. RIs provide a significant discount (up to 72%) over On-Demand pricing in exchange for a one- or three-year commitment, ensuring cost minimization while guaranteeing capacity availability in the specified Availability Zone.

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Spot Instances

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On-Demand Instances

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Dedicated Hosts

Question 11

A company has an Amazon DynamoDB table that stores historical data. The table is accessed infrequently but when queried requires consistent single-digit millisecond latency. The SysOps administrator wants to minimize storage costs while maintaining the required performance. Which DynamoDB table class should the administrator use?

Accepted Answer

DynamoDB Standard-IA (Infrequent Access). DynamoDB Standard-IA (Infrequent Access) is designed for tables that are accessed less than once per month, offering lower storage costs than DynamoDB Standard while maintaining the same single-digit millisecond latency for queries. Since the table stores historical data with infrequent access but requires consistent performance, Standard-IA minimizes storage costs without sacrificing latency.

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DynamoDB Standard

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DynamoDB On-Demand

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DynamoDB Provisioned

Question 12

A company uses Amazon CloudFront to deliver content to a global audience. The origin is an Application Load Balancer in us-east-1. The SysOps administrator wants to reduce costs by minimizing the number of requests that reach the origin server. Which action should the administrator take?

Accepted Answer

Enable CloudFront Origin Shield.. CloudFront Origin Shield acts as an additional caching layer in front of the origin, reducing the load on the origin by consolidating requests from multiple edge locations. This minimizes the number of requests that reach the Application Load Balancer, directly lowering origin request costs and improving cache hit ratio.

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Configure multiple origins for failover.

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Enable CloudFront Web Application Firewall (WAF) integration.

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Increase the cache TTL for CloudFront distributions.

Question 13

A company runs a development Amazon EC2 instance that is only used during business hours (9 AM to 5 PM). The SysOps administrator wants to reduce compute costs. Which action should be taken?

Accepted Answer

Schedule the instance to automatically stop during off-hours and start before business hours. The instance is only needed during business hours (9 AM to 5 PM), so automatically stopping it during off-hours and starting it before business hours eliminates compute charges for idle time. Stopped instances incur no EC2 instance running costs (only storage and EBS volume costs), directly reducing the compute bill. AWS Instance Scheduler or a simple cron-based Lambda function can enforce this schedule reliably.

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Use On-Demand instances

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Use a Reserved Instance

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Use a Spot instance

Question 14

A company uses an Amazon DynamoDB table with on-demand capacity mode for a variable workload. The SysOps administrator notices high costs and wants to reduce them without affecting application performance. Which action should the administrator take?

Accepted Answer

Switch the table to provisioned capacity mode with auto scaling.. Switching from on-demand to provisioned capacity with auto scaling reduces costs for variable workloads by allowing you to set a lower base capacity and scale only when needed, avoiding the premium per-request pricing of on-demand mode. Auto scaling adjusts read/write capacity based on actual utilization, ensuring application performance is maintained while eliminating the cost overhead of paying for every request at on-demand rates.

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Enable DynamoDB Accelerator (DAX) for caching.

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Implement DynamoDB Global Tables to distribute data across regions.

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Set a Time to Live (TTL) attribute to automatically expire old items.

Question 15

A company uses an Amazon DynamoDB table with provisioned capacity. The average write usage is 500 write capacity units (WCU) but regularly spikes to 2,000 WCU during business hours. The SysOps administrator wants to reduce costs without affecting performance during the spikes. Which solution should the administrator implement?

Accepted Answer

Enable DynamoDB auto scaling. DynamoDB auto scaling allows the table to automatically adjust its provisioned write capacity between a minimum and maximum range based on actual traffic. By setting the minimum WCU to cover the average usage (500) and the maximum to handle the spikes (2,000), the administrator pays only for the baseline capacity most of the time, while the service scales up during spikes without manual intervention or over-provisioning.

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Switch to DynamoDB on-demand capacity mode

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Purchase reserved capacity for 2,000 WCU

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