SOA-C02 Cost and Performance Optimization Practice Test 12 — 15 Questions

Question 1

A company hosts a web application on EC2 instances behind an Application Load Balancer (ALB). The application experiences variable traffic patterns with occasional spikes. The current setup uses On-Demand instances in an Auto Scaling group with a simple scaling policy based on average CPU utilization. The team wants to optimize cost while ensuring that the application can handle spikes in traffic. What should the team do to reduce cost?

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

Accepted Answer

Configure the Auto Scaling group to use a mixed instances policy with Spot Instances for a portion of the capacity and On-Demand for the remainder.. A mixed instances policy with Spot Instances for a portion of the capacity reduces cost by leveraging unused EC2 capacity at a lower price, while On-Demand instances handle the base load and ensure availability during spikes. Spot Instances are ideal for variable and fault-tolerant workloads like this web application. Option A (target tracking based on request count) improves scaling responsiveness but does not directly reduce cost; it still uses On-Demand instances. Option B (scheduled scaling) is not suitable for unpredictable traffic spikes, as it only adds capacity at fixed times. Option D (Reserved Instances) provides discounts for steady-state usage but does not help with variable traffic or spikes, and may lead to over-provisioning or wasted capacity.

Answer

Switch to a target tracking scaling policy based on request count per target.

Answer

Implement scheduled scaling to add capacity during known peak hours.

Answer

Purchase Reserved Instances for the minimum expected capacity to get a discount.

Question 2

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 3

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. 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 4

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.. 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 5

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.. 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 6

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 7

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 8

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

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AWS Trusted Advisor

Answer

Amazon CloudWatch Dashboard

Question 9

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.. 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 10

A company runs an e-commerce application on Amazon EC2 instances behind an Auto Scaling group. The application has a predictable baseline load from 8 AM to 8 PM daily and low load overnight. The SysOps administrator wants to optimize costs while ensuring sufficient capacity for the baseline load. Which purchasing option and scaling strategy should the administrator use?

Accepted Answer

Use Reserved Instances for the predicted baseline and On-Demand for any unexpected spikes.. Reserved Instances provide a significant discount (up to 72%) over On-Demand for predictable, steady-state workloads like the 8 AM to 8 PM baseline. On-Demand instances then cover any unexpected spikes without requiring upfront commitment, ensuring cost optimization while maintaining capacity for the predictable load.

Answer

Use On-Demand instances for the baseline and Spot Instances for any additional capacity.

Answer

Use Dedicated Hosts for all instances to maximize cost savings.

Answer

Use Spot Instances for all instances to minimize costs.

Question 11

A company stores application log files in an Amazon S3 bucket. The logs are accessed frequently for the first 30 days, then rarely accessed but must be retrievable within 12 hours. After 1 year, the logs must be archived for compliance with a retention period of 5 years, during which retrievals are expected to be extremely rare (one or two per year) and retrieval time of 12 hours is acceptable. The SysOps administrator wants to minimize storage costs. Which S3 lifecycle policy configuration should be used?

Accepted Answer

After 30 days, transition to S3 Glacier Flexible Retrieval; after 365 days, transition to S3 Glacier Deep Archive; delete after 5 years.. It uses S3 Glacier Flexible Retrieval for the first year after the initial 30 days, which meets the 12-hour retrieval requirement at lower cost than S3 Standard-IA, then transitions to S3 Glacier Deep Archive for the remaining 4 years to minimize storage costs for extremely rare retrievals. The lifecycle policy transitions objects after 30 days to S3 Glacier Flexible Retrieval (retrieval time minutes to 12 hours), then after 365 days to S3 Glacier Deep Archive (retrieval time 12 hours), and deletes after 5 years, aligning with the access patterns and compliance retention.

Answer

After 30 days, transition to S3 Standard-IA; after 365 days, transition to S3 Glacier Deep Archive; delete after 5 years.

Answer

After 30 days, transition to S3 Glacier Flexible Retrieval; delete after 5 years.

Answer

After 30 days, transition to S3 Glacier Deep Archive; delete after 5 years.

Question 12

A company runs a web application on Amazon EC2 instances in an Auto Scaling group. The application uses Amazon EBS volumes (gp2) for data storage. The SysOps administrator notices that the storage costs are high, and the application's IOPS requirements are consistently below 3000. The administrator wants to reduce storage costs without affecting performance. Which action should the administrator take?

Accepted Answer

Convert the EBS volumes from gp2 to gp3 volume type.. Gp3 volumes offer a baseline performance of 3000 IOPS and 125 MB/s throughput at a lower cost than gp2 volumes, making them ideal for workloads with IOPS requirements consistently below 3000. By converting from gp2 to gp3, the administrator can reduce storage costs without any performance impact, as gp3 provides the same or better baseline performance at a lower price per GB.

Answer

Modify the EBS volumes to use Provisioned IOPS (io1) volumes and set IOPS to 2000.

Answer

Implement an Amazon EBS snapshot lifecycle policy to delete old snapshots and reduce storage costs.

Answer

Enable EBS optimization on the EC2 instances to improve throughput and reduce costs.

Question 13

A company runs a batch processing application on Amazon EC2 instances every night. The job takes exactly 1 hour to complete and is time-sensitive. The SysOps administrator wants to minimize compute costs while ensuring the job can be interrupted and resumed if needed. Which EC2 purchasing option is most cost-effective?

Accepted Answer

Spot Instances. Spot Instances are the most cost-effective option because the batch job is fault-tolerant (can be interrupted and resumed) and runs for exactly 1 hour nightly. Spot Instances offer up to 90% discount compared to On-Demand, and with the ability to handle interruptions via checkpointing, they meet the requirement for cost minimization while supporting resumption.

Answer

On-Demand Instances

Answer

Reserved Instances (Standard 1-year)

Answer

Dedicated Hosts

Question 14

A company runs a production Amazon DynamoDB table with provisioned capacity of 1000 write capacity units (WCU). The table experiences unpredictable spikes up to 2000 WCU, causing throttling. The SysOps administrator wants to minimize cost while handling the spikes. Which solution should be used?

Accepted Answer

Switch to on-demand capacity mode.. Switching to on-demand capacity mode eliminates throttling during unpredictable spikes by automatically scaling write capacity up to the required 2000 WCU without any manual intervention or pre-provisioning. This minimizes cost because you pay only for the actual reads and writes consumed, avoiding the fixed cost of over-provisioning for peak capacity that may be rarely used.

Answer

Increase provisioned WCU to 2000 to cover the peak.

Answer

Enable DynamoDB Auto Scaling with minimum 1000, maximum 2000 WCU.

Answer

Use a DynamoDB Accelerator (DAX) cache.

Question 15

A company runs a production web application on a single Amazon EC2 instance. The application experiences a predictable and steady workload 24/7. The SysOps administrator wants to minimize compute costs for this instance while ensuring it remains available during the expected workload. Which EC2 purchasing option should the administrator use?

Accepted Answer

Reserved Instances. Reserved Instances (RIs) are the most cost-effective option for a predictable, steady-state workload running 24/7. By committing to a 1- or 3-year term, you receive a significant discount (up to 72%) compared to On-Demand pricing, while still ensuring the instance remains available for the expected workload. This matches the requirement to minimize compute costs without sacrificing availability.

Answer

On-Demand Instances

Answer

Spot Instances

Answer

Dedicated Hosts