SAA-C03 Design Cost-Optimized Architectures Practice Test 5 — 15 Questions

Question 1

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 2

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.

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 3

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 4

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.. Option A is correct because 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 5

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.. Option A is correct because 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 6

A startup has three sandbox accounts and one production account. The CTO wants lower cost and operational overhead while keeping central purchasing and spend visibility. Which two actions are best? Select two.

Accepted Answer

Enable consolidated billing under AWS Organizations so discounts and shared purchasing apply across accounts.. Option A is correct because enabling consolidated billing under AWS Organizations aggregates usage across all accounts, allowing the startup to benefit from volume discounts and Reserved Instance sharing, which lowers overall costs. This also provides a single payer account for central purchasing and spend visibility through the consolidated billing console.

Answer

Move each sandbox to its own payer account to isolate spend from the rest.

Answer

Buy Dedicated Hosts for sandbox workloads to get a lower blended rate.

Answer

Disable AWS Budgets because consolidated billing already solves visibility.

Question 7

A team serves static content (JavaScript, CSS, images) from S3 through CloudFront. After a recent release, CloudFront reports a low cache hit ratio and the S3 origin receives a much higher request rate. The site still works, but billing shows higher origin and data transfer costs. Which change is most likely to improve cache hit ratio and reduce origin load?

Accepted Answer

Configure a CloudFront cache policy (or update HTTP cache-control headers) to increase TTLs for versioned static assets and enable compression for text assets.. Option A is correct because increasing TTLs for versioned static assets via a CloudFront cache policy or HTTP Cache-Control headers ensures that CloudFront caches these immutable objects for longer periods, reducing the number of requests forwarded to the S3 origin. Enabling compression for text assets reduces the data transferred from origin to edge, further lowering origin load and costs. This directly addresses the low cache hit ratio and high origin request rate described in the scenario.

Answer

Disable CloudFront access logging so fewer requests are recorded and billing decreases automatically.

Answer

Set the distribution’s origin to use S3 Transfer Acceleration to reduce the number of requests hitting S3.

Answer

Force CloudFront to forward query strings to the origin for all static content so the latest versions are always fetched.

Question 8

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 9

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 10

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 11

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 12

A batch-processing system runs only during business hours (08:00–18:00 UTC). The jobs are restartable, and the architecture can tolerate occasional interruptions. Which approach minimizes cost while meeting the business-hours constraint?

Accepted Answer

Use Spot Instances for the batch workload during business hours and scale the capacity down to zero outside that window.. Option B is correct because Spot Instances offer significant cost savings (up to 90% compared to On-Demand) and are ideal for fault-tolerant, restartable batch workloads. The architecture can tolerate interruptions, and scaling to zero outside business hours ensures no compute costs are incurred when the system is not needed.

Answer

Use only On-Demand instances during business hours and scale to zero outside those hours.

Answer

Purchase a 3-year Reserved Instance and keep the workload running 24/7 to use the commitment fully.

Answer

Purchase Reserved Instances and disable scaling so the fleet stays within the commitment regardless of job demand.

Question 13

A service runs in private subnets. It must call AWS APIs (for example, S3 and Secrets Manager). The team currently sends all outbound traffic through a NAT Gateway, and NAT charges have become a major cost driver. The workload must not traverse the public internet. What change most directly reduces NAT Gateway cost while maintaining private connectivity to those AWS services?

Accepted Answer

Replace the NAT Gateway route with VPC endpoints: use a Gateway VPC endpoint for S3 and an Interface VPC endpoint for Secrets Manager.. Option B is correct because VPC endpoints allow private connectivity to AWS services without traversing the internet or a NAT Gateway. A Gateway VPC endpoint for S3 uses route table entries to reach S3 privately, and an Interface VPC endpoint for Secrets Manager uses an elastic network interface with a private IP. This eliminates NAT Gateway data processing charges entirely while keeping traffic within the AWS network.

Answer

Continue using the NAT Gateway but reduce CloudWatch log retention to 1 day.

Answer

Launch a bastion host in a public subnet and force private instances to use SSH tunneling for API calls.

Answer

Switch to public subnets and attach security groups with the same rules to limit inbound access.

Question 14

An S3 bucket stores user-uploaded media. Most objects are never read again, but compliance requires keeping them for at least 18 months. Retrieval is rare and typically only needed during investigations. The current design keeps everything in S3 Standard, increasing storage cost. Which configuration best optimizes cost while meeting the retention and rare-access requirements?

Accepted Answer

Use an S3 lifecycle policy to transition objects to S3 Glacier Deep Archive after 30 days, and expire them after 18 months.. Option B is correct because S3 Glacier Deep Archive offers the lowest storage cost for data that is rarely accessed and has a flexible retrieval time (12 hours for standard retrievals). The lifecycle policy transitions objects after 30 days to minimize Standard costs, and expiration after 18 months ensures compliance by deleting objects exactly when the retention period ends, avoiding manual cleanup.

Answer

Move all objects to S3 Glacier Instant Retrieval immediately upon upload and disable lifecycle policies.

Answer

Keep objects in S3 Standard but compress them with a custom process to reduce storage size.

Answer

Enable S3 Intelligent-Tiering for all objects and delete any object not accessed within 24 hours.

Question 15

A static web application uses CloudFront with an S3 origin for assets (JavaScript, CSS, images). After deploying a new frontend build, the CloudFront cache hit ratio dropped significantly because the S3 origin receives many repeated requests for the same assets. The team notices that requests now include the Authorization header in asset requests. Which change is most likely to restore cache efficiency and reduce origin request costs?

Accepted Answer

Update the CloudFront cache policy so that Authorization is excluded from the cache key for static asset paths.. The drop in cache hit ratio is caused by the Authorization header being included in asset requests, which makes each request unique from CloudFront's perspective, preventing cache reuse. By updating the CloudFront cache policy to exclude the Authorization header from the cache key for static asset paths, CloudFront can treat identical asset requests as cache hits, restoring cache efficiency and reducing origin load.

Answer

Keep the Authorization header but increase the cache TTL to 1 year to reduce revalidation frequency.

Answer

Remove CloudFront and serve assets directly from the S3 website endpoint to reduce CloudFront charges.

Answer

Switch the S3 origin from private access to public access so CloudFront can cache assets more effectively.