SOA-C02 Cost and Performance Optimization Practice Test 10 — 15 Questions

Question 1

A SysOps administrator needs to reduce data transfer costs for a web application hosted on EC2 instances in a VPC. The application serves content to users over the internet. Which TWO actions will help reduce data transfer costs? (Choose TWO.)

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

Accepted Answer

Use a VPC Gateway Endpoint for Amazon S3 to keep S3 traffic within AWS.. Option B is correct because a VPC Gateway Endpoint for Amazon S3 routes S3 traffic privately within the AWS network instead of through a NAT Gateway or internet gateway, eliminating NAT data processing charges and internet data transfer fees for that traffic. Option C is correct because Amazon CloudFront caches static content at edge locations closer to users, reducing the volume of data transferred out from the EC2 instances and lowering EC2 data transfer out charges. Option A is incorrect because Direct Connect is for private connectivity to AWS, not for serving public internet users, and private subnets do not reduce internet egress costs. Option D is incorrect because an Application Load Balancer distributes traffic but does not by itself reduce data transfer costs and adds LCU charges. Option E is incorrect because a larger NAT Gateway does not lower per-GB NAT data processing charges and may increase cost.

Answer

Move all instances to private subnets and use AWS Direct Connect for user access.

Answer

Use an Application Load Balancer to distribute traffic.

Answer

Use a larger NAT Gateway to improve throughput.

Question 2

A SysOps administrator reviews the CloudWatch metric data for an EC2 instance. The instance runs a web application that experiences high traffic between 12:00 and 14:00 UTC daily. The administrator wants to optimize costs while maintaining performance. What should the administrator do?

Accepted Answer

Create an Auto Scaling group with a scheduled scaling policy to add instances during peak hours.. The instance has low CPU utilization most of the day but spikes to 90% during peak hours. Using a scheduled Auto Scaling to add instances during peak hours ensures performance without over-provisioning. Option A is wrong because the instance is not constantly at high utilization. Option B is wrong because upgrading instance size increases cost during off-peak hours. Option D is wrong because a larger instance would be underutilized.

Answer

Convert the instance to a Reserved Instance to reduce hourly cost.

Answer

Replace the instance with a larger instance type and enable detailed monitoring.

Answer

Increase the instance size to handle peak load at all times.

Question 3

A company runs a web application on EC2 instances behind an Application Load Balancer. The application experiences variable traffic patterns. What is the MOST cost-effective way to ensure the application scales based on demand?

Accepted Answer

Use EC2 Auto Scaling with a target tracking scaling policy based on average CPU utilization.. A target tracking scaling policy based on average CPU utilization automatically adjusts the number of EC2 instances to maintain a target metric (e.g., 50% CPU), scaling out during high demand and scaling in during low demand. This is the most cost-effective approach for variable traffic patterns as it eliminates over-provisioning and manual intervention, directly aligning capacity with real-time demand.

Answer

Provision a fixed number of EC2 instances that can handle peak load at all times.

Answer

Use EC2 Auto Scaling with a scheduled scaling policy that adds instances during business hours.

Answer

Use EC2 Auto Scaling with a manual scaling plan that requires an administrator to adjust the desired capacity.

Question 4

A company uses AWS Lambda functions to process messages from an SQS queue. The Lambda function is configured with a reserved concurrency of 100. The SQS queue receives unpredictable spikes of up to 10,000 messages per second. The function takes about 1 second to process a message. The SysOps team notices that during spikes, messages are being throttled and appear in the DLQ. How can the team resolve this while optimizing cost?

Accepted Answer

Increase reserved concurrency to 1000 and enable batch processing with a batch size of 10 in the SQS event source mapping.. Increasing reserved concurrency to 1000 allows the Lambda function to scale to handle the spike of 10,000 messages per second, and enabling batch processing with a batch size of 10 reduces the number of invocations, which optimizes cost by processing up to 10 messages per invocation instead of one. Option A is wrong because reducing reserved concurrency would throttle even more messages, increasing DLQ traffic. Option C is wrong because using EC2 adds operational overhead and does not leverage Lambda's serverless scaling, increasing complexity and cost. Option D is wrong because Lambda does not use instance types; memory and timeout adjustments do not directly address concurrency limitations or batch processing.

Answer

Reduce the reserved concurrency to 10 to force the function to process messages more slowly.

Answer

Provision an EC2 fleet to poll the SQS queue and invoke the Lambda function.

Answer

Increase the Lambda function memory and timeout to use a larger instance type.

Question 5

A company uses CloudFront to distribute content globally. They want to reduce data transfer costs and improve performance for users. What feature should they enable?

Accepted Answer

Enable Origin Shield to create a central caching layer.. Origin Shield adds an additional caching layer between CloudFront edge locations and the origin, consolidating origin fetches through a single regional cache. This reduces the number of requests that reach the origin, lowering data transfer costs and improving cache hit ratios and latency for users. It is the specific CloudFront feature designed for this cost-and-performance goal.

Answer

Configure multiple origins with failover.

Answer

Enable Lambda@Edge to modify requests and responses.

Answer

Increase the TTL for cache behaviors to the maximum allowed value.

Question 6

A company stores 1 PB of data in Amazon S3 Standard. The data is accessed frequently for the first 30 days, then rarely accessed afterwards. The company needs to optimize storage costs. What should they do?

Accepted Answer

Configure an S3 Lifecycle policy to transition objects to S3 Standard-IA after 30 days, then to S3 Glacier Deep Archive after 90 days.. It uses an S3 Lifecycle policy to automatically transition objects to S3 Standard-IA after 30 days (when access drops), then to S3 Glacier Deep Archive after 90 days for long-term cold storage. This balances cost and access needs: Standard-IA offers lower storage cost than Standard for infrequent access, and Glacier Deep Archive provides the lowest cost for rarely accessed data after 90 days. The policy automates the transitions, avoiding manual effort and ensuring cost optimization without data loss.

Answer

Move all objects to S3 Intelligent-Tiering immediately.

Answer

Delete objects older than 30 days using S3 Lifecycle expiration.

Answer

Manually change the storage class of each object to S3 Glacier Deep Archive after 30 days.

Question 7

A company uses an Application Load Balancer (ALB) to distribute traffic to EC2 instances. The SysOps team wants to reduce costs by ensuring that idle capacity is minimized. Which configuration should they implement?

Accepted Answer

Configure an Auto Scaling group with a target tracking scaling policy based on ALB request count per target.. A target tracking scaling policy based on ALB request count per target automatically adjusts the number of EC2 instances to keep the request count per instance at a specified target value. This directly ties scaling to actual traffic demand, minimizing idle capacity while maintaining performance. It is the most cost-efficient and responsive configuration for an ALB-fronted workload.

Answer

Configure an Auto Scaling group with a step scaling policy based on CPU utilization.

Answer

Increase the number of EC2 instances in the Auto Scaling group to handle peak load.

Answer

Set the Auto Scaling group desired capacity to the maximum expected load.

Question 8

A company wants to reduce costs for their Amazon RDS for PostgreSQL database. Which TWO actions would help achieve this?

Accepted Answer

Stop the database instance during non-business hours.. Option B is correct because stopping an RDS for PostgreSQL instance during non-business hours eliminates instance-hour charges while it is stopped (storage charges still apply), directly reducing compute costs for a database that is not needed around the clock. Option E is correct because purchasing a Reserved Instance for the DB instance provides a significant discount (up to roughly 69% versus On-Demand for a 3-year, all-upfront term) in exchange for a commitment to a specific instance family and Region, lowering the effective hourly rate for steady-state workloads. Option A is not cost-reducing because Multi-AZ runs a synchronous standby replica in a second AZ, roughly doubling instance and storage cost in exchange for high availability. Option C is a safety control that prevents accidental deletion and has no positive effect on cost. Option D increases cost, since extending backup retention to 35 days keeps more automated backup storage beyond the free allocation and incurs additional backup storage charges.

Answer

Enable Multi-AZ deployment for high availability.

Answer

Enable deletion protection to prevent accidental deletion.

Answer

Increase the backup retention period to 35 days.

Question 9

A company has an S3 bucket policy as shown. A developer tries to upload an object using the AWS CLI without the --no-verify-ssl flag. What will happen?

Accepted Answer

The upload will succeed because the CLI uses HTTPS by default.. The bucket policy denies requests that do not use secure transport (HTTP) but allows HTTPS requests. The AWS CLI uses HTTPS by default, and since the developer did not use --no-verify-ssl, the request is made over HTTPS. Therefore, the upload succeeds. Option D is correct. Option A is incorrect because the CLI uses HTTPS, not HTTP. Option B is incorrect because the policy does not deny all s3:* actions; it only denies requests over HTTP. Option C is incorrect because the policy requires HTTPS, and the CLI complies, so the upload does not fail.

Answer

The upload will succeed only if the developer uses HTTP.

Answer

The upload will fail because the policy denies all s3:* actions.

Answer

The upload will fail because the policy requires explicit HTTPS.

Question 10

A company runs a web application on EC2 instances behind an ALB. They want to optimize costs for variable traffic patterns while maintaining high availability. Which solution is MOST cost-effective?

Accepted Answer

Use a mix of On-Demand and Spot Instances in an Auto Scaling group with a target tracking scaling policy.. The most cost-effective because it combines On-Demand Instances for baseline capacity and Spot Instances for burstable traffic, leveraging lower Spot prices while maintaining high availability through Auto Scaling with a target tracking policy. Option A is wrong because Dedicated Hosts are expensive and provide no cost benefit for variable traffic. Option C is wrong because Reserved Instances require a 1- or 3-year commitment and are not suitable for variable traffic; they are better for steady-state workloads. Option D is wrong because using only On-Demand Instances is more expensive than using a mix that includes Spot Instances.

Answer

Use Dedicated Hosts to run the application and share resources across multiple accounts.

Answer

Purchase Reserved Instances for the expected baseline capacity and use On-Demand for spikes.

Answer

Use only On-Demand EC2 Instances with an Auto Scaling group to handle variable traffic.

Question 11

A company is using AWS CloudFormation to deploy infrastructure. They want to reduce costs by identifying unused resources. Which AWS service should they use to monitor and report on resource utilization and cost?

Accepted Answer

AWS Trusted Advisor. AWS Trusted Advisor provides cost optimization checks, including identifying idle resources and underutilized instances, helping reduce costs. Option B (AWS Config) is incorrect because it tracks configuration changes and compliance, not cost optimization. Option C (Amazon CloudWatch) is incorrect because it monitors metrics and logs, not cost optimization directly. Option D (AWS CloudTrail) is incorrect because it logs API activity, not cost or resource utilization.

Answer

AWS Config

Answer

Amazon CloudWatch

Answer

AWS CloudTrail

Question 12

A SysOps administrator is reviewing the monthly AWS bill and notices a significant cost for data transfer from EC2 to the internet. The EC2 instances are in a VPC and serve content to users. Which action would MOST effectively reduce data transfer costs?

Accepted Answer

Use Amazon CloudFront as a content delivery network (CDN).. Using Amazon CloudFront as a CDN caches content at edge locations closer to users, reducing the amount of data transferred directly from EC2 instances to the internet. This lowers data transfer out (DTO) costs because CloudFront has lower data transfer rates and can also cache content, reducing the load on EC2. The question specifies data transfer from EC2 to the internet, so offloading to CloudFront is the most effective cost reduction.

Answer

Use VPC endpoints to connect to S3 and DynamoDB.

Answer

Move the EC2 instances to a different AWS Region with lower data transfer rates.

Answer

Use a NAT Gateway to route traffic through a single IP.

Question 13

A company runs a batch processing job every night that takes 2 hours on a single m5.xlarge EC2 instance. The job is fault-tolerant and can be interrupted. The SysOps administrator wants to reduce costs. Which solution is MOST cost-effective?

Accepted Answer

Use a Spot Instance with a Spot Fleet that includes a fallback to On-Demand if Spot is not available.. The most cost-effective solution is to use a Spot Instance with a Spot Fleet that includes a fallback to On-Demand if Spot is not available (Option B). The job is fault-tolerant and can be interrupted, making it ideal for Spot Instances which offer significant cost savings (up to 90% compared to On-Demand). The Spot Fleet with an On-Demand fallback ensures the job completes even if Spot capacity is unavailable. Option A (On-Demand with CloudWatch alarm) does not reduce costs since On-Demand is more expensive. Option C (Dedicated Host) is costly and unnecessary for a batch job. Option D (Reserved Instance) requires a 1- or 3-year commitment and is not cost-effective for a 2-hour daily job.

Answer

Use an On-Demand instance and set up a CloudWatch alarm to stop it when the job completes.

Answer

Use a Dedicated Host to run the job.

Answer

Purchase a Reserved Instance for the m5.xlarge instance.

Question 14

A company has an S3 bucket that stores millions of small objects (1-10 KB) and uses S3 Standard storage. The bucket receives frequent PUT requests and occasional GET requests. The monthly bill shows high costs for S3 PUT requests. Which action would reduce costs?

Accepted Answer

Aggregate small objects into larger files (e.g., 1 MB) before uploading to S3.. S3 PUT request charges are per-request, so uploading millions of tiny objects incurs millions of PUT charges. Aggregating small objects into larger files (e.g., 1 MB) before upload dramatically reduces the number of PUT requests and therefore the request cost. This directly targets the line item the bill shows as high.

Answer

Move the objects to S3 Glacier Deep Archive to reduce storage cost.

Answer

Move the objects to S3 Intelligent-Tiering to optimize storage costs.

Answer

Use S3 Lifecycle policies to transition objects to S3 Standard-IA after 30 days.

Question 15

A SysOps administrator wants to monitor the cost and usage of AWS resources for different departments. Which AWS service should they use to tag resources and generate cost allocation reports?

Accepted Answer

AWS Cost Explorer with cost allocation tags. AWS Cost Explorer with cost allocation tags is the correct answer because it allows you to activate user-defined or AWS-generated tags as cost allocation tags, then filter and group cost and usage data by those tags to produce per-department reports. Cost Explorer is the native billing tool for visualizing spend over time and supports tag-based breakdowns directly. Trusted Advisor, Budgets, and Config do not generate cost allocation reports by tag.

Answer

AWS Trusted Advisor

Answer

AWS Budgets

Answer

AWS Config