SOA-C02 Cost and Performance Optimization Practice Test 8 — 15 Questions

Question 1

An application running on Amazon EC2 generates a large number of small files that are stored temporarily and deleted after 24 hours. The files are accessed frequently within the first hour and then rarely. Which Amazon S3 storage class is MOST cost-effective for this use case?

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

Accepted Answer

S3 Intelligent-Tiering. S3 Intelligent-Tiering (Option B). This storage class automatically moves objects between a frequent access tier and an infrequent access tier based on changing access patterns, making it cost-effective for unpredictable or shifting access patterns. In this use case, files are accessed frequently in the first hour and then rarely, so Intelligent-Tiering will initially store them in the frequent access tier and then move them to the infrequent access tier after 30 days of no access, reducing costs. Option A (S3 Glacier Deep Archive) is unsuitable due to a 180-day minimum storage charge and retrieval times of hours, which does not match the 24-hour retention. Option C (S3 One Zone-Infrequent Access) is not ideal because it has a 30-day minimum storage charge and is designed for data accessed infrequently but with quick retrieval, not for a pattern that starts with frequent access. Option D (S3 Standard) would be unnecessarily expensive for the data after the first hour when it is rarely accessed.

Answer

S3 Glacier Deep Archive

Answer

S3 One Zone-Infrequent Access

Answer

S3 Standard

Question 2

A SysOps administrator notices that an Amazon RDS for MySQL instance has high read activity. The application performs many read queries but few writes. The database is currently a single db.r5.large instance. What change would improve read performance and reduce cost?

Accepted Answer

Create a read replica and use a smaller instance type for the replica.. Creating a read replica offloads read traffic from the primary instance, improving performance for read-heavy workloads. Using a smaller instance type for the replica reduces cost compared to scaling up the primary. Option A is wrong because Multi-AZ provides high availability via a standby instance that cannot serve reads; it does not improve read performance. Option B (increasing instance size) is a vertical scaling approach that increases cost without the same cost-efficiency as a read replica. Option C is incorrect because migrating to DynamoDB would require application changes and may not be compatible with the existing MySQL schema and queries.

Answer

Enable Multi-AZ for high availability and use the standby for reads.

Answer

Increase the instance size to db.r5.xlarge.

Answer

Migrate the database to Amazon DynamoDB.

Question 3

A company has a production AWS account that uses Consolidated Billing with several member accounts. The finance team wants to identify the top cost drivers and allocate costs to different departments. Which AWS tool should be used to visualize and allocate costs?

Accepted Answer

AWS Cost Explorer. AWS Cost Explorer allows visualization and filtering of costs by tags, accounts, and services, enabling cost allocation and identification of top cost drivers. AWS Organizations (A) is used to centrally manage policies and accounts but does not provide cost visualization. AWS Trusted Advisor (B) offers best practice recommendations but not detailed cost analysis. AWS Budgets (D) sets budget alerts but does not provide historical cost exploration or allocation.

Answer

AWS Organizations

Answer

AWS Trusted Advisor

Answer

AWS Budgets

Question 4

A company uses Amazon CloudFront to distribute content globally. The operations team notices that the data transfer costs are higher than expected. The origin server is an S3 bucket in us-east-1. Which change would reduce data transfer costs?

Accepted Answer

Enable compression for compressible content.. Enabling compression reduces the amount of data transferred from CloudFront to viewers, directly lowering data transfer costs. Option A (Lambda@Edge to resize images) can reduce image sizes but adds compute costs and may not be as effective as compression. Option B (increasing default TTL) reduces origin requests but does not reduce data transfer from CloudFront to viewers. Option C (multiple S3 buckets in different regions) increases complexity and may increase costs due to cross-region replication or multiple origins. Thus, D is the correct choice.

Answer

Use Lambda@Edge to resize images on the fly.

Answer

Increase the default TTL for objects.

Answer

Use multiple S3 buckets in different regions as origins.

Question 5

A company runs a stateless web application on EC2 instances in an Auto Scaling group. The application is deployed across multiple Availability Zones. During a recent traffic spike, the Auto Scaling group launched more instances than expected, increasing costs. The SysOps administrator needs to prevent unexpected scaling while maintaining availability. What should the administrator do?

Accepted Answer

Configure scaling cooldowns to limit launch rate.. Configuring scaling cooldowns prevents additional instances from being launched too quickly during traffic spikes, thereby controlling cost while maintaining availability. Option A is incorrect because changing from dynamic to simple scaling does not inherently prevent rapid scaling; simple scaling also responds to alarms. Option B is incorrect because lowering the maximum instance count could limit the ability to handle spikes, causing performance issues. Option C is incorrect because reducing to one Availability Zone would eliminate fault tolerance and increase risk of downtime. Thus, D is the correct choice.

Answer

Use a simple scaling policy instead of a dynamic scaling policy.

Answer

Set a lower maximum instance count in the Auto Scaling group.

Answer

Reduce the number of Availability Zones to one.

Question 6

A company is using Amazon EBS volumes for a high-performance database. The volumes are gp2 type. The database workload is write-intensive, and the company is experiencing high costs due to provisioned IOPS. The database team wants to maintain performance while reducing costs. Which EBS volume type should the company use?

Accepted Answer

gp3. gp3 volumes are the correct choice because they provide a baseline performance that is independent of volume size, and customers only pay for provisioned IOPS above the baseline. This makes them cost-effective for write-intensive database workloads. Option A (sc1) is wrong because Cold HDD volumes are designed for infrequently accessed data and offer low IOPS, making them unsuitable for high-performance databases. Option B (st1) is wrong because Throughput Optimized HDD volumes are optimized for large, sequential workloads, not random I/O typical of databases. Option C (io2 Block Express) is wrong because while it offers high performance, it is more expensive than gp3 for workloads that do not require the extreme performance of io2.

Answer

sc1 (Cold HDD)

Answer

st1 (Throughput Optimized HDD)

Answer

io2 Block Express

Question 7

A SysOps administrator wants to receive alerts when the estimated charges for an AWS account exceed a certain threshold. Which AWS service should be used?

Accepted Answer

AWS Budgets. AWS Budgets enables you to set custom cost and usage budgets and receive alerts when your actual or forecasted costs exceed your budget thresholds. This is the correct service for receiving alerts on estimated charges. Option A (AWS Trusted Advisor) provides cost optimization recommendations but does not send billing alerts. Option B (AWS Cost Explorer) allows you to analyze your costs but does not send proactive alerts. Option C (Amazon CloudWatch billing metric) does have billing metrics, but to set alerts on those metrics you must use AWS Budgets; CloudWatch itself is not the service for budget alerts.

Answer

AWS Trusted Advisor

Answer

AWS Cost Explorer

Answer

Amazon CloudWatch (billing metric)

Question 8

A company runs a production workload on Amazon EC2 instances. The SysOps administrator wants to implement a cost optimization strategy that does not compromise availability. Which TWO actions should the administrator take?

Accepted Answer

Use Spot Instances for fault-tolerant and stateless workloads.. Using Spot Instances for fault-tolerant and stateless workloads reduces costs by leveraging unused EC2 capacity, and purchasing Reserved Instances for baseline capacity provides a significant discount for predictable usage; both strategies maintain availability because Spot Instances are suitable for workloads that can handle interruptions, and Reserved Instances guarantee capacity availability. Option B (identifying and terminating idle instances) is not among the best two actions because it does not address the balance between baseline and variable demand, and it could inadvertently affect availability if idle instances are part of a cluster or needed for scaling. Option D (using smaller instance types) may degrade performance and compromise availability. Option E (using a single Availability Zone) reduces fault tolerance and increases the risk of downtime.

Answer

Identify and terminate idle instances.

Answer

Use smaller instance types for all workloads.

Answer

Use a single Availability Zone to reduce data transfer costs.

Question 9

A company is using Amazon S3 to store log files. The logs are accessed frequently for the first 30 days and then rarely, but must be retained for 7 years for compliance. Which TWO actions would optimize storage costs while maintaining accessibility?

Accepted Answer

Transition objects to S3 Glacier Deep Archive after 365 days.. Only options B and C are correct. Transitioning to S3 Standard-IA after 30 days reduces cost for infrequent access after the first month. Transitioning to S3 Glacier Deep Archive after one year is cost-effective for 7-year retention while still allowing retrieval within hours. Option A is wrong because deleting objects after 90 days violates the 7-year compliance requirement. Option D is wrong because moving directly to Glacier after 30 days is premature and not the most cost-effective; Standard-IA is more appropriate for the infrequent access pattern. Option E is wrong because S3 Intelligent-Tiering has monitoring costs and is not optimal for predictable access patterns; lifecycle policies are more cost-effective.

Answer

Delete objects older than 90 days.

Answer

Transition objects directly to S3 Glacier after 30 days.

Answer

Use S3 Intelligent-Tiering to automatically move objects.

Question 10

A SysOps administrator needs to reduce costs for an Amazon RDS for PostgreSQL database. The database is used for a reporting application that only runs during business hours (9 AM to 5 PM). Which TWO actions would reduce costs without losing data?

Accepted Answer

Take a snapshot before stopping to preserve data.. Stopping the database during off-hours (Option E) stops billing for compute hours while preserving the data. Taking a snapshot before stopping (Option A) ensures data is preserved, but it is not required to save costs—stopping alone saves costs. However, the question requires preserving data, so combining stopping with a snapshot is the safest approach. Option B (deleting and restoring) risks data loss and is inefficient. Option C (converting to a read replica) does not directly reduce costs. Option D (Multi-AZ) increases costs.

Answer

Delete the database during off-hours and restore it each morning.

Answer

Convert the database to a read replica of another database.

Answer

Use a Multi-AZ cluster for high availability.

Question 11

A company is running a production web application on EC2 instances behind an ALB. The application experiences predictable traffic spikes during business hours. Which cost optimization strategy would be MOST effective?

Accepted Answer

Configure Scheduled Scaling to add instances before the spike and remove after.. The most effective cost optimization strategy because Scheduled Scaling allows you to increase capacity predictably before traffic spikes and decrease afterward, ensuring you only pay for what you need. Option B is incorrect because Spot Instances can be interrupted and are not suitable for production workloads that require high availability. Option C is incorrect because using larger instances does not dynamically adjust to spikes and may lead to over-provisioning during low traffic. Option D is incorrect because On-Demand instances are more expensive than using scheduled scaling with a mix of Reserved Instances or Savings Plans to cover the baseline and scheduled scaling for the spikes.

Answer

Use Spot Instances for the entire workload.

Answer

Use larger instance types to handle the spikes without scaling.

Answer

Use On-Demand instances exclusively to handle the spikes.

Question 12

A company is using AWS Cost Explorer to analyze spending. They want to receive an email alert when costs exceed a certain threshold. Which service should they use?

Accepted Answer

AWS Budgets. AWS Budgets can send alerts when costs exceed thresholds. Option A (AWS Trusted Advisor) is wrong because it provides recommendations for cost optimization but does not send alerts based on cost thresholds. Option B (AWS Cost Explorer) is wrong because it is used for analyzing cost and usage data, not for sending alerts. Option C (Amazon CloudWatch) is wrong because CloudWatch monitors AWS resources and applications, but it does not natively monitor AWS costs or send cost threshold alerts.

Answer

AWS Trusted Advisor

Answer

AWS Cost Explorer

Answer

Amazon CloudWatch

Question 13

A company has an EC2-based application that runs at inconsistent times. The workloads are fault-tolerant and can be interrupted. Which purchasing option provides the most cost savings?

Accepted Answer

Spot Instances. Spot Instances. Spot Instances offer the largest discount (up to 90%) for workloads that are fault-tolerant and can be interrupted. Reserved Instances (A) require a 1- or 3-year commitment and are best for steady-state workloads. On-Demand Instances (B) provide no discount. Dedicated Hosts (C) are expensive and designed for specific licensing or compliance requirements, not cost savings.

Answer

Reserved Instances

Answer

On-Demand Instances

Answer

Dedicated Hosts

Question 14

A SysOps administrator is troubleshooting high CPU utilization on an RDS for MySQL instance. The application is read-heavy. Which optimization technique would improve performance and potentially reduce costs?

Accepted Answer

Implement RDS Read Replicas to offload read traffic.. Read Replicas alleviate CPU pressure on the primary RDS instance by offloading read queries to read-only replicas. This improves performance for read-heavy workloads and can allow you to use a smaller instance class, reducing costs. Option A is wrong because deleting unused indexes may improve write performance but not CPU utilization for read-heavy workloads. Option C is wrong because increasing storage size does not directly reduce CPU usage. Option D is wrong because Multi-AZ provides high availability, not performance improvement.

Answer

Delete unused indexes from the database.

Answer

Increase the allocated storage size.

Answer

Enable Multi-AZ deployment for failover support.

Question 15

A company wants to monitor the performance of its EC2 instances and receive alerts when CPU utilization exceeds 80% for 10 minutes. Which AWS service should be used?

Accepted Answer

Amazon CloudWatch. Amazon CloudWatch can monitor CPU utilization metrics for EC2 instances and trigger alarms when a threshold (e.g., 80% for 10 minutes) is exceeded. Option B (AWS CloudTrail) is wrong because it records API activity, not performance metrics. Option C (AWS Config) is wrong because it evaluates resource configurations, not performance. Option D (VPC Flow Logs) is wrong because it captures network traffic information, not CPU usage.

Answer

AWS CloudTrail

Answer

AWS Config

Answer

VPC Flow Logs