SAA-C03 Design Cost-Optimized Architectures Practice Test 12 — 15 Questions

Question 1

An internal team runs a report-generation job once per day. It typically finishes in a few minutes, and even on its slowest days it still completes in under 15 minutes. The team wants to reduce operational overhead and pay primarily for actual runtime instead of keeping servers running 24/7. Which AWS approach best matches these goals?

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

Accepted Answer

Use AWS Lambda triggered by a schedule (for example, EventBridge) to run the report at the required time.. AWS Lambda is the ideal choice because it is a serverless compute service that runs code only when triggered, aligning with the requirement to pay primarily for actual runtime. By using Amazon EventBridge (CloudWatch Events) to invoke the Lambda function on a daily schedule, the team eliminates the need to provision or manage servers, and the job's typical runtime of a few minutes (under 15 minutes, Lambda's maximum execution timeout) fits perfectly within Lambda's constraints.

Answer

Deploy the job on EC2 instances and keep them running continuously for the daily schedule.

Answer

Run the job in an RDS database using stored procedures scheduled by the database engine.

Answer

Use an Auto Scaling group with a fixed minimum size of one instance and disable scaling.

Question 2

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), which perfectly matches the always-on API fleet that runs at a steady 65% CPU utilization. This plan applies to any EC2 instance family, region, or compute service (including Fargate and Lambda), giving flexibility while reducing costs for the predictable baseline load.

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 3

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 capacity up and down based on demand, so you only pay for the resources you use. This eliminates the need to provision for peak traffic and avoids paying for large idle database instances, making it cost-optimized for unpredictable workloads.

Answer

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

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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 4

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.. A is correct because S3 Intelligent-Tiering automatically moves objects between access tiers based on changing access patterns, eliminating the need to manually guess or configure lifecycle rules. It charges a small monthly monitoring fee per object but avoids the higher cost of keeping cold data in S3 Standard, making it the cheapest hands-off approach for unpredictable access followed by cold storage.

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 5

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) rather than peak guesses directly reduces compute and memory costs. Since the peak dashboard traffic lasts only three hours, the database can be scaled down for the remaining 21 hours, avoiding over-provisioning. This is a fundamental cost-optimization strategy for RDS without requiring application changes.

Answer

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

Answer

Increase provisioned IOPS permanently so the monthly bill drops.

Question 6

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 server workloads, and they are typically more cost-effective than gp2 volumes when similar performance is adequate. By using gp3, you avoid paying for provisioned IOPS that you do not need, directly reducing storage costs without sacrificing recovery options.

Answer

Keep unattached volumes around for troubleshooting after instance termination.

Answer

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

Question 7

A company runs an application on EC2 instances in private subnets. The instances must access Amazon S3, and the team currently routes all outbound traffic to the internet through a NAT Gateway. Monthly NAT Gateway charges increased significantly, even though the application only needs to call S3 (not access other public internet services). Which change will most directly reduce NAT Gateway charges while keeping S3 access working?

Accepted Answer

Create a gateway VPC endpoint for S3 and update the private route tables so S3 traffic uses the endpoint instead of the NAT Gateway.. A gateway VPC endpoint for S3 allows instances in private subnets to access S3 over the AWS network without traversing the internet. By updating the private route tables to direct S3 traffic to the endpoint, the NAT Gateway is bypassed, eliminating the per-GB data processing charges and hourly NAT Gateway fees for that traffic. This directly reduces costs while maintaining secure, private access to S3.

Answer

Enable S3 Transfer Acceleration on the bucket to reduce the number of S3 calls that go through the NAT Gateway.

Answer

Switch the EC2 instances to public subnets so S3 calls can use direct internet routing without NAT.

Answer

Increase the NAT Gateway TCP idle timeout so fewer connections are billed separately for S3 traffic.

Question 8

A media processing pipeline runs batch jobs on EC2. The jobs can tolerate interruptions because they checkpoint progress to durable storage and can restart. The total workload is variable week-to-week, and there is no need to guarantee capacity at specific times. To reduce compute cost while maintaining correctness, what EC2 purchase option and approach is the best fit?

Accepted Answer

Use EC2 Spot Instances with interruption handling and restart from checkpoints.. Spot Instances offer up to 90% cost savings compared to On-Demand and are ideal for fault-tolerant, stateless workloads that can checkpoint progress to durable storage. Since the batch jobs can tolerate interruptions and restart from checkpoints, Spot Instances provide the lowest compute cost while maintaining correctness. No other purchase option achieves the same level of cost reduction for this variable, interruption-tolerant workload.

Answer

Use All Upfront Reserved Instances sized for the average weekly workload to minimize cost.

Answer

Use On-Demand Instances and scale only during business hours to reduce idle time.

Answer

Use Savings Plans with a fixed hourly commitment to ensure capacity for the entire year.

Question 9

A development team expects their EC2 utilization to average about 40% of capacity across the next year. They want to lower costs but need flexibility to change instance families and sizes as requirements evolve (for example, moving from compute-optimized to memory-optimized instances). Which AWS purchasing commitment best meets the goal of reducing cost while keeping flexibility?

Accepted Answer

Compute Savings Plans, sized to the expected average usage, because they provide savings across instance families and usage types.. Compute Savings Plans offer the best balance of cost reduction and flexibility for this scenario. They provide up to 66% savings in exchange for a commitment to a consistent amount of compute usage (measured in $/hour), but unlike Reserved Instances, they automatically apply to any EC2 instance family, size, OS, or region (within a given AWS region). This allows the team to switch from compute-optimized to memory-optimized instances as needs evolve without losing the discount, directly meeting the requirement for flexibility while lowering costs.

Answer

All Upfront EC2 Instance Reserved Instances for a single instance family to maximize discount.

Answer

Spot Instances for the entire workload so they can avoid commitments entirely.

Answer

On-Demand Instances with increased Auto Scaling to match the peak month only.

Question 10

An S3 bucket stores user-uploaded images. Access patterns are unpredictable: some objects are never read again, while others are occasionally retrieved months later. The team wants to reduce storage cost without having to manually track access frequency or run periodic analyses. Which S3 storage and lifecycle approach is the best fit?

Accepted Answer

Enable S3 Intelligent-Tiering so objects can automatically move between access tiers based on observed access patterns.. S3 Intelligent-Tiering is the best fit because it automatically moves objects between access tiers (frequent, infrequent, archive instant, archive) based on changing access patterns, eliminating the need for manual tracking or lifecycle rules. This optimizes storage costs for unpredictable access patterns without requiring you to define fixed time-based transitions or perform periodic analyses.

Answer

Use S3 Glacier Instant Retrieval for all objects immediately to minimize storage cost.

Answer

Create a lifecycle rule that transitions objects to Standard-IA after a fixed 30 days, regardless of access.

Answer

Keep all objects in S3 Standard and reduce costs by enabling server access logging compression.

Question 11

A company stores user uploads in an S3 bucket. Objects are accessed rarely after upload, but when an object is accessed, it must be retrievable quickly (minutes to a few hours). Objects must be retained for at least 18 months. The team wants to reduce storage cost while meeting these requirements. Which lifecycle configuration best fits these requirements?

Accepted Answer

After 30 days, transition objects to S3 Glacier Instant Retrieval, and after 18 months, expire (delete) the objects.. It transitions objects to S3 Glacier Instant Retrieval after 30 days, which provides millisecond retrieval for rarely accessed data, meeting the quick retrieval requirement. The 18-month expiration ensures compliance with the retention policy while minimizing storage costs compared to keeping data in S3 Standard.

Answer

Keep all objects in S3 Standard permanently to avoid lifecycle transition fees.

Answer

After 30 days, transition objects to S3 Intelligent-Tiering, and set expiration to 12 months.

Answer

After 30 days, transition objects to S3 Glacier Deep Archive, and set expiration to 18 months.

Question 12

An EC2 workload runs in one region on a single instance type. For the last month, CloudWatch metrics show average CPU utilization of 12% and no sustained memory pressure. The team wants to reduce cost while maintaining the current performance level. What is the best first step?

Accepted Answer

Use AWS Compute Optimizer to get recommendations for instance type and size changes.. AWS Compute Optimizer analyzes historical utilization metrics (CPU, memory, I/O) and provides actionable recommendations for right-sizing instances. Given the average CPU utilization of only 12% and no memory pressure, Compute Optimizer will likely recommend a smaller instance type or family that matches the workload's actual resource needs, reducing cost without affecting performance.

Answer

Increase the instance size to reduce the risk of performance regression.

Answer

Switch to Spot Instances immediately to reduce cost regardless of utilization.

Answer

Disable detailed monitoring to lower CloudWatch charges.

Question 13

A company hosts an application on EC2 instances in private subnets. The instances must (1) read objects from Amazon S3 and (2) retrieve secrets from AWS Secrets Manager. The team currently sends all outbound traffic through a NAT gateway to reach both services. They want to reduce monthly cost while keeping traffic private (no internet egress) and without changing application logic. Which change is the most cost-effective?

Accepted Answer

Create a Gateway VPC endpoint for S3 and an Interface VPC endpoint for Secrets Manager, and ensure the subnet route tables / endpoint routing directs those service calls to the endpoints instead of the NAT gateway.. Gateway VPC Endpoints for S3 and Interface VPC Endpoints for Secrets Manager allow private connectivity to these AWS services without traversing the internet or a NAT gateway. This eliminates NAT gateway hourly charges and data processing fees, reducing costs while keeping traffic within the AWS network. The application logic remains unchanged as the endpoints are accessed via the same DNS names, with route tables directing traffic to the endpoints instead of the NAT gateway.

Answer

Keep the NAT gateway, but add AWS WAF rules to block non-service outbound requests to reduce NAT usage.

Answer

Disable IPv4 on the VPC subnets and rely on IPv6-only egress to reduce NAT gateway costs.

Answer

Replace the NAT gateway with a VPC firewall appliance instance to proxy outbound calls and reduce NAT fees.

Question 14

A media company runs a fleet of EC2 instances using Auto Scaling across multiple instance families (for example, m-series and c-series) in a single region. The business wants to commit to steady usage for one year to reduce cost, but the application team must retain flexibility to switch instance families and scale up/down as demand changes. They need the cost-reduction approach that best matches this flexibility. Which option is the best fit?

Accepted Answer

Purchase Compute Savings Plans so the commitment applies regardless of instance family changes within the selected scope.. Compute Savings Plans provide the most flexibility because they apply to any EC2 instance family (including m-series and c-series) within a region, automatically adjusting to instance family changes and scaling. This matches the requirement to commit to steady usage for one year while retaining the ability to switch families and scale up/down, offering up to 66% savings over On-Demand without locking the application to a specific instance type.

Answer

Purchase Standard Reserved Instances tied to a specific instance family and region, so the application can only run on the selected family.

Answer

Purchase Spot Instances for all capacity and disable On-Demand fallback to guarantee the lowest cost.

Answer

Rely only on On-Demand and reduce cost by using a CloudFront-only approach for all dynamic content.

Question 15

A media company uploads raw video thumbnails to an S3 bucket every hour. The application needs these thumbnails for active browsing for the first 7 days. After day 7, access becomes rare. Requirements: - Objects must remain available in S3 for at least 180 days total. - After day 7, the team can tolerate retrieval latency in the range of minutes to hours. - They want to minimize storage cost while keeping the ability to read objects (no application changes required). Which storage strategy is the most cost-optimized fit?

Accepted Answer

Use a lifecycle rule to transition objects to S3 Glacier Flexible Retrieval after day 7 and expire them after day 180.. S3 Glacier Flexible Retrieval provides retrieval times from minutes to hours, which matches the tolerance for rare access after day 7, and offers the lowest storage cost among the options for data that is rarely accessed. A lifecycle rule transitions objects from S3 Standard (used for the first 7 days of active browsing) to Glacier Flexible Retrieval on day 7, then expires them after day 180, meeting the 180-day retention requirement without application changes.

Answer

Use a bucket-level lifecycle rule to transition objects to S3 Standard-IA on day 7 and then expire them after day 180.

Answer

Keep all objects in S3 Standard for 180 days, and enable S3 Intelligent-Tiering only if the bucket’s access frequency is above a threshold.

Answer

Use a lifecycle rule to transition objects to S3 Glacier Instant Retrieval after day 7 and expire them after day 180.