SAA-C03 Design Cost-Optimized Architectures — 50 Questions

Question 1

An internal rendering job runs on EC2 workers in an Auto Scaling group. Each job writes checkpoints every few minutes to S3 and can resume from the latest checkpoint after an interruption. The queue depth varies sharply, and the team wants the lowest possible compute cost. Which two changes should they make? Select two.

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

Accepted Answer

Run the worker fleet on EC2 Spot Instances.. Spot Instances can be interrupted with a two-minute warning, and since the rendering job writes checkpoints to S3 every few minutes and can resume from the latest checkpoint, it is fault-tolerant to interruptions. This allows the team to leverage the significantly lower cost of Spot Instances (up to 90% off On-Demand) while maintaining job completion, achieving the lowest compute cost for variable queue depths.

Answer

Purchase Dedicated Hosts so the fleet keeps physical servers reserved for the workload.

Answer

Run the entire fleet on On-Demand Instances to avoid any interruption risk.

Answer

Move the workers to AWS Outposts to keep compute close to the data.

Question 2

Match each data-retention scenario to the most cost-effective Amazon S3 storage class. Assume the retrieval pattern and access-latency requirement are the most important constraints.

Accepted Answer

S3 Standard: Data accessed frequently; need low latency. S3 Standard is for frequent access; Intelligent-Tiering optimizes cost for unknown patterns; Standard-IA for infrequent but rapid access; Glacier Flexible Retrieval for minutes; Glacier Deep Archive for hours.

Answer

S3 Glacier Flexible Retrieval: Data accessed infrequently but requires rapid access when needed; retrieval time milliseconds

Answer

S3 Glacier Deep Archive: Data that can be retrieved within 1-5 minutes

Question 3

Match each workload to the AWS pricing option that most directly minimizes cost while still meeting the stated flexibility requirements. Use each option once.

Accepted Answer

Spot Instances: A fault-tolerant data processing job that can be interrupted and resumed. Spot Instances are cheapest for fault-tolerant workloads; Reserved Instances offer discounts for steady usage; On-Demand is flexible for short tests; Savings Plans provide lower rates for committed use; Dedicated Hosts meet compliance for strict workloads.

Answer

Spot Instances: A production database server running 24/7 with predictable load

Answer

On-Demand: A fault-tolerant batch job that can handle interruptions

Question 4

Match each workload to the most cost-effective compute model or service choice. Focus on how often the workload runs, whether it is interruption-tolerant, and how much administration the team wants to avoid.

Accepted Answer

Short-lived automated tasks that run every minute: AWS Lambda. Lambda is ideal for short, frequent tasks; Batch on Fargate for nightly jobs; Spot Instances for fault-tolerant workloads; Reserved Instances or Savings Plans are more cost-effective for consistent steady-state loads like a stateful e-commerce platform; ECS Fargate reduces management.

Answer

Stateful e-commerce platform with consistent load: On-Demand EC2 instances

Question 5

A service in private subnets downloads product images from Amazon S3 and stores job state in DynamoDB. A NAT Gateway is currently the only route to AWS services, and the monthly bill is dominated by NAT data processing charges. Which two changes will most directly reduce that cost? Select two.

Accepted Answer

Create a gateway VPC endpoint for Amazon S3.. A is correct because a gateway VPC endpoint for Amazon S3 allows instances in private subnets to access S3 directly over the AWS network without traversing the internet or a NAT Gateway. This eliminates NAT data processing charges for S3 traffic, which is the dominant cost driver in this scenario.

Answer

Add an internet gateway and move the instances into public subnets.

Answer

Replace the NAT Gateway with a Site-to-Site VPN connection.

Answer

Create an interface endpoint for S3 instead of a gateway endpoint.

Question 6

Match each private-networking or content-delivery scenario to the AWS feature that most directly reduces cost while meeting the connectivity requirement.

Accepted Answer

CloudFront: Content delivery with low latency to global users. Each AWS feature directly reduces cost for the given scenario: CloudFront for latency, VPC Peering for intra-region, Direct Connect for hybrid, Transit Gateway for inter-region, Shield+CloudFront for security, and Global Accelerator for inter-region data transfer costs.

Answer

Transit Gateway: Point-to-point connectivity between two VPCs

Answer

Global Accelerator: Low-latency content delivery to edge locations

Question 7

A containerized service runs in private subnets and retrieves secrets from AWS Secrets Manager and configuration parameters from AWS Systems Manager Parameter Store on startup. A NAT Gateway is currently used only for these AWS API calls, and the security team wants to eliminate that recurring charge. Which two endpoints should be added? Select two.

Accepted Answer

Create an interface VPC endpoint for AWS Secrets Manager.. AWS Secrets Manager is accessed via API calls over HTTPS, and an interface VPC endpoint (powered by AWS PrivateLink) allows private connectivity to the service without traversing the internet or a NAT Gateway. This eliminates the need for the NAT Gateway for Secrets Manager traffic, reducing costs and improving security by keeping traffic within the AWS network.

Answer

Create a gateway VPC endpoint for Amazon S3 instead.

Answer

Add an Internet Gateway and send the traffic through public subnets.

Answer

Replace the NAT Gateway with a NAT instance.

Question 8

A line-of-business application runs on EC2 instances 24/7 with predictable usage for the next year. The application will stay in the same Region, and the team does not want to manage capacity interruptions. Which two purchase options can reduce cost compared with pure On-Demand pricing? Select two.

Accepted Answer

Buy Compute Savings Plans for the expected steady usage.. Compute Savings Plans (A) offer a flexible discount (up to 66%) in exchange for a 1- or 3-year commitment to a consistent amount of compute usage (measured in $/hour), automatically applying to any EC2 instance family, region, or even AWS Fargate/Lambda. This reduces cost compared to On-Demand while avoiding capacity interruptions, as the commitment covers the predictable steady-state usage. Standard Reserved Instances (B) provide a similar discount (up to 72%) for a specific instance family in a specific region, also with a 1- or 3-year term, and guarantee capacity for the specified AZ if you choose a zonal reservation, ensuring no interruptions.

Answer

Move the fleet to Spot Instances.

Answer

Use Dedicated Hosts to reserve physical servers for the application.

Answer

Stay entirely on On-Demand Instances because they are already the cheapest option.

Question 9

A compliance archive writes one log file per day to Amazon S3. The logs are almost never accessed after day 30, but if they are needed they must still be retrievable in milliseconds. They must be deleted automatically after one year. Which two lifecycle settings should you apply? Select two.

Accepted Answer

Transition the objects to S3 Glacier Instant Retrieval after 30 days.. S3 Glacier Instant Retrieval provides millisecond retrieval times for archived data, meeting the requirement that logs must be retrievable in milliseconds after 30 days. This storage class is designed for long-lived, rarely accessed data that still needs immediate access, making it ideal for compliance archives that are almost never accessed but must be available instantly when needed.

Answer

Transition the objects to S3 Standard-IA after 30 days.

Answer

Keep the logs in S3 Standard indefinitely and delete them manually when needed.

Answer

Replicate the logs to another Region for cheaper archival storage.

Question 10

An application stores user-uploaded binaries in S3. Access is unpredictable for the first month, then most objects become cold. The team wants the cheapest approach that avoids manually guessing access patterns. Which two actions are best? Select two.

Accepted Answer

Enable S3 Intelligent-Tiering on the bucket.. S3 Intelligent-Tiering automatically moves objects between access tiers (frequent, infrequent, archive instant, and deep archive) based on changing access patterns, without manual lifecycle rules. This is ideal for unpredictable access in the first month followed by cold storage, as it optimizes cost by charging only for the storage tier actually used per object, with a small monthly monitoring fee per object.

Answer

Keep all objects in S3 Standard because lifecycle transitions add too much management.

Answer

Copy all binaries to Amazon EFS so retrieval is faster.

Answer

Disable versioning because S3 Intelligent-Tiering needs it to work.

Question 11

A photo studio stores original project archives in Amazon S3. Objects are read heavily for 14 days after upload, occasionally during the next 11 months, and almost never after one year. The team wants the lowest storage cost while keeping retrieval within minutes during the first year. Which three actions are best? Select three.

Accepted Answer

Keep new objects in S3 Standard for the first 14 days.. Option A is correct because S3 Standard is the right class for the first 14 days, when the objects are read heavily and require immediate, low-latency access with no retrieval fees. Option B is correct because after 14 days the access pattern becomes occasional, and S3 Standard-IA offers lower storage pricing than S3 Standard while still providing millisecond retrieval, satisfying the requirement to keep retrieval within minutes during the first year. Option D is correct because after one year the archives are almost never accessed, so S3 Glacier Deep Archive provides the lowest storage cost of the available classes, and its standard retrieval time (within 12 hours) is acceptable since the minutes-level retrieval requirement only applies to the first year. Option C is not appropriate because S3 Glacier Flexible Retrieval costs more than Deep Archive for data that is almost never accessed after one year, and the question asks for the lowest storage cost. Option E is incorrect because S3 Lifecycle rules work with or without versioning; disabling versioning is not required and would remove a useful data-protection feature.

Answer

Transition objects to S3 Glacier Flexible Retrieval after 14 days.

Answer

Disable versioning to make the lifecycle rules work correctly.

Question 12

A media company runs a 24/7 ingestion API on EC2 behind an Application Load Balancer and a nightly transcoding job that can resume from checkpoints. The API fleet runs at roughly 65 percent CPU all day, while the batch workers sit idle most of the time. The company wants to cut compute cost without risking the API. Which two changes should they make? Select two.

Accepted Answer

Purchase a Compute Savings Plan for the always-on API fleet.. A is correct because a Compute Savings Plan offers the largest discount (up to 66%) in exchange for a 1- or 3-year commitment to a consistent amount of compute usage (measured in $/hour), regardless of instance family, region, or OS. The API fleet runs at a steady 65% CPU 24/7, making it an ideal candidate for this flexible, cost-saving commitment without locking into a specific instance type.

Answer

Replace the API fleet with Dedicated Hosts to lock in lower rates.

Answer

Buy Standard Reserved Instances for the batch workers and keep them running 24/7.

Answer

Increase the worker Auto Scaling minimum to prevent Spot interruptions.

Question 13

A company processes product-image uploads in bursts. Each transform takes up to ten minutes, and every job can be retried safely from the beginning. The current EC2 worker fleet is idle most of the day. Which two changes most reduce cost and idle capacity? Select two.

Accepted Answer

Buffer jobs in Amazon SQS and let workers scale from queue depth.. Option A is correct because decoupling the bursty uploads with Amazon SQS lets the EC2 worker fleet scale out only when queue depth rises and scale in when the queue drains, eliminating the idle capacity the current always-on fleet wastes. Option B is correct because AWS Fargate Spot runs containers on spare capacity at a discount, and since each transform can be retried safely from the beginning, Spot interruptions are tolerable and further reduce cost versus on-demand workers. Option C is wrong because a fixed Auto Scaling group with a higher minimum keeps more instances running than needed, preserving idle capacity and cost. Option D is wrong because Reserved Instances require steady, predictable usage to pay off, and this workload is highly bursty. Option E is wrong because restricting processing to a nightly window does not reduce the total compute needed and does not address idle capacity; it merely shifts when the fleet is busy.

Answer

Keep a fixed fleet of m6i.large instances in an Auto Scaling group with a higher minimum.

Answer

Use Reserved Instances for the workers even though demand is highly bursty.

Answer

Process uploads only during a nightly window so the fleet looks busier.

Question 14

A product catalog system uses a relational database for orders and a simple key-value profile store for shopping carts. Traffic is unpredictable, and the company wants to avoid paying for large idle database instances. Which two choices are best? Select two.

Accepted Answer

Use Aurora Serverless v2 for the relational order system.. Aurora Serverless v2 automatically scales compute and memory capacity based on application demand, making it ideal for unpredictable traffic. It eliminates the need to provision for peak load, reducing costs by scaling to zero when idle. This matches the requirement to avoid paying for large idle database instances.

Answer

Keep both workloads on large provisioned RDS instances and add read replicas for the cart store.

Answer

Use DynamoDB provisioned capacity with a fixed minimum despite the unpredictable traffic.

Answer

Replace the relational order system with a wide-column table to reduce SQL licensing.

Question 15

A SaaS vendor has a steady 24/7 control plane on ECS and several small event-driven tasks that currently run on a separate always-on service. Management wants the billing discount that applies across both ECS and Lambda usage without committing to a specific instance family. Which two actions are best? Select two.

Accepted Answer

Buy a Compute Savings Plan for the predictable baseline usage.. Option A is correct because a Compute Savings Plan provides a discount that applies across ECS, Lambda, and Fargate usage, and it does not require committing to a specific instance family, which matches the requirement to cover both ECS and Lambda with one flexible commitment. Option B is correct because moving the small event-driven tasks from an always-on service to AWS Lambda makes them pay-per-invocation and lets their usage be covered by the same Compute Savings Plan discount as the ECS control plane. Option C is wrong because an EC2 Instance Savings Plan is tied to a specific instance family and Region and does not apply to Lambda usage. Option D is wrong because Spot Instances can be interrupted and are unsuitable for a steady 24/7 control plane, and Spot does not provide the cross-service ECS/Lambda discount described. Option E is wrong because increasing ECS desired count does not eliminate Lambda or produce the desired cross-service billing discount.

Answer

Buy an EC2 Instance Savings Plan tied to one instance family for all workloads.

Answer

Use Spot Instances for the control plane because it is the largest bill.

Answer

Increase the ECS desired count so Lambda can be removed.

Question 16

A retailer runs a reporting-heavy relational app on Amazon RDS MySQL. Peak dashboard traffic lasts only three hours each day, but the database is sized for the peak all day. The business wants lower cost without rewriting the application. Which three actions are best? Select three.

Accepted Answer

Right-size the writer based on actual utilization instead of peak guesses.. Right-sizing the RDS instance based on actual utilization metrics (e.g., CPU, memory, connections) directly reduces cost by eliminating over-provisioning for the 3-hour peak. This is a fundamental cost-optimization practice that avoids paying for idle capacity during the remaining 21 hours.

Answer

Migrate to DynamoDB immediately because every relational workload is more expensive.

Answer

Increase provisioned IOPS permanently so the monthly bill drops.

Question 17

A fleet of test servers is rebuilt every week from AMIs. EBS volumes are often left behind after termination, and the team creates daily snapshots of every volume even when nothing changes. Which three actions most reduce storage cost while preserving recovery options? Select three.

Accepted Answer

Use gp3 for new EBS volumes instead of gp2 when similar performance is enough.. Gp3 volumes offer a baseline performance that is often sufficient for test servers, and they are typically more cost-effective than gp2 volumes for the same amount of storage. By using gp3, you avoid paying for the additional IOPS that gp2 includes by default, which can reduce costs when the workload does not require high performance. This directly addresses the goal of reducing storage costs while maintaining adequate performance for recovery purposes.

Answer

Keep unattached volumes around for troubleshooting after instance termination.

Answer

Raise provisioned IOPS on every volume so snapshot restore time feels faster.

Question 18

A SaaS company uses an S3 bucket for database backups created daily. Backups are rarely restored; the company’s documented RTO is 24 hours, and the compliance policy requires backups be kept for 90 days. The team currently stores all backups in S3 Standard, which is costly.

Which single lifecycle policy change is most cost-optimized while still meeting the 24-hour RTO and 90-day retention?

Accepted Answer

Add a lifecycle rule to transition backups older than 1 day to S3 Glacier Flexible Retrieval, and keep them until day 90.. S3 Glacier Flexible Retrieval offers retrieval times ranging from minutes to hours, which comfortably meets the 24-hour RTO, while providing significant cost savings over S3 Standard for data that is rarely accessed. Transitioning backups older than 1 day to this storage class reduces costs without compromising the 90-day retention requirement.

Answer

Add a lifecycle rule to transition backups older than 1 day to S3 Glacier Instant Retrieval, and keep them until day 90.

Answer

Add a lifecycle rule to transition backups older than 1 day to S3 Glacier Deep Archive, and keep them until day 90 with no restore configuration.

Answer

Add a lifecycle rule to transition backups older than 1 day to S3 One Zone-IA, and delete them after 7 days.

Question 19

A startup has a stable production web service that runs continuously (24/7) on AWS. They have consistent compute requirements for the next 1 year, but the instance size and family might change as they optimize performance. To reduce cost while maintaining flexibility across instance types, which purchasing option should they consider?

Accepted Answer

Compute Savings Plans. Compute Savings Plans offer the lowest prices (up to 66% off On-Demand) while allowing flexibility to change instance family, size, OS, and region. This matches the startup's need for consistent 1-year compute usage with potential instance type changes during optimization.

Answer

Reserved Instances with a fixed instance type

Answer

Spot Instances

Answer

On-Demand Instances

Question 20

A company stores compliance reports in Amazon S3. Objects are written once and rarely accessed. They need to keep the data for 3 years. When retrieval is needed for an audit, the reports can be restored within hours (not minutes). What storage class should the company use for new objects, assuming minimal operational overhead?

Accepted Answer

S3 Glacier Flexible Retrieval. S3 Glacier Flexible Retrieval is the correct choice because it is designed for long-term archival data that is rarely accessed, with retrieval times ranging from minutes to hours. It offers a lower storage cost than S3 Standard while still meeting the 3-year retention requirement and the acceptable retrieval window of 'within hours'. This minimizes operational overhead as objects are automatically transitioned to the appropriate storage tier without manual lifecycle management.

Answer

S3 Standard

Answer

S3 Intelligent-Tiering

Answer

S3 Glacier Deep Archive