SAA-C03 Design Cost-Optimized Architectures Practice Test 2 — 15 Questions

Question 1

A workload runs in private subnets. It must access AWS services such as Amazon S3, but the company wants to avoid using a NAT Gateway to reduce outbound networking costs. What is the best solution?

Accepted Answer

Create VPC endpoints for the required AWS services and route traffic to them. VPC endpoints (Gateway Endpoints for S3 and DynamoDB, or Interface Endpoints for other services) allow instances in private subnets to access AWS services privately without traversing the internet or a NAT Gateway. This eliminates NAT Gateway data processing and hourly charges, directly reducing outbound networking costs while keeping traffic within the AWS network.

Answer

Attach Elastic IP addresses to instances in private subnets

Answer

Install a NAT Gateway in every subnet to minimize routing hops

Answer

Open outbound internet access with a security group rule to reach service endpoints directly

Question 2

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 3

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 4

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 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) 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 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 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 7

An application runs on EC2 in us-east-1 and frequently reads objects from an S3 bucket that is physically located in us-west-2. The finance team reports unexpectedly high inter-Region data transfer charges because the application retrieves objects for many user requests. A constraint: the bucket in us-west-2 must remain the system of record for compliance, but the application can read from a replica in us-east-1.

What should the solutions architect do to minimize network spend while meeting the compliance constraint?

Accepted Answer

Enable S3 Cross-Region Replication from the us-west-2 source bucket to a destination bucket in us-east-1, and update the app to read from the us-east-1 bucket.. S3 Cross-Region Replication (CRR) automatically replicates objects from the source bucket in us-west-2 to a destination bucket in us-east-1, satisfying the compliance requirement that the us-west-2 bucket remains the system of record. By updating the application to read from the us-east-1 bucket, all read traffic stays within the same region, eliminating inter-region data transfer charges for object retrievals. This approach directly addresses the cost issue while preserving the original bucket as the authoritative source.

Answer

Create an interface VPC endpoint for S3 in us-east-1 and keep all object reads pointing to the us-west-2 bucket.

Answer

Use VPC peering between two regions and route all requests to the us-west-2 bucket over the peering link.

Answer

Use Route 53 latency-based routing to send users to a us-west-2 web endpoint and keep the S3 bucket unchanged.

Question 8

A media company runs a batch job that processes image thumbnails. The job can be restarted from checkpoints and does not have user-facing SLAs. The batch capacity can tolerate interruptions. Which EC2 purchasing option is the best cost optimization choice?

Accepted Answer

Use EC2 Spot Instances, accepting the possibility of interruptions and using checkpoints to resume.. Spot Instances offer significant cost savings (up to 90% compared to On-Demand) and are ideal for fault-tolerant, stateless, or checkpointable workloads. Since the batch job can restart from checkpoints and tolerates interruptions, Spot Instances provide the best cost optimization without compromising functionality.

Answer

Use On-Demand Instances because interruptions are not allowed for production workloads.

Answer

Purchase Reserved Instances because they provide a discount regardless of the workload timing.

Answer

Buy Savings Plans because they guarantee capacity and remove the risk of interruptions entirely.

Question 9

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 10

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

Question 11

A company keeps daily database backups in an S3 bucket. They may restore from backups during the first 30 days if there is an issue. After 30 days, backups are rarely restored, but must be retained for 2 years. Which lifecycle strategy most cost-effectively meets these requirements?

Accepted Answer

Use an S3 lifecycle policy to keep backups in S3 Standard for 30 days, then transition them to S3 Glacier Deep Archive for the remainder of the 2-year retention period.. It balances cost and compliance: backups are kept in S3 Standard for the first 30 days when restores are frequent, ensuring low-latency access, then transitioned to S3 Glacier Deep Archive for the remaining retention period. S3 Glacier Deep Archive offers the lowest storage cost (approximately $0.00099/GB/month) for long-term retention, and the lifecycle policy automates the transition without manual intervention. This approach minimizes storage costs while meeting the 2-year retention requirement.

Answer

Delete backups after 30 days to avoid storage costs, since restores are rare.

Answer

Keep all backups in S3 Standard for the entire 2-year retention period.

Answer

Move backups to S3 Glacier Deep Archive immediately after creation, even for the first 30 days.

Question 12

A media company runs a 24/7 recommendation engine on EC2 in one AWS Region. The workload is interruption-intolerant, and the team expects steady usage but may change instance families and sizes during planned optimizations. Compared to the current On-Demand setup, they want the lowest cost while avoiding the rigidity of locking to a specific instance type.

What should the solutions architect recommend?

Accepted Answer

Purchase a Compute Savings Plan for the expected steady hourly usage in that Region.. B is correct because a Compute Savings Plan offers the lowest cost for steady-state workloads without locking to a specific instance type, providing up to 66% discount compared to On-Demand while allowing flexibility to change instance families, sizes, OS, or tenancy within a Region. This matches the requirement for cost savings and flexibility during planned optimizations.

Answer

Switch the instances to Spot Instances and use interruption handling because it is the largest discount.

Answer

Purchase a Standard Reserved Instance tied to a single specific instance type for the next 3 years.

Answer

Keep On-Demand and rely on Auto Scaling to reduce capacity when utilization is low.

Question 13

A marketing team runs a report-generation process that must execute once per day at 02:00 UTC. It usually completes in 10315 minutes, but sometimes takes up to 45 minutes due to varying data volumes. They currently run the workload on an EC2 instance that is always on, which wastes money during off-hours. The team wants to minimize operational overhead and pay mainly for actual execution time.

What is the best architecture choice?

Accepted Answer

Use an EventBridge schedule to run the report as an Amazon ECS task on AWS Fargate and write results to S3.. AWS Fargate allows the report-generation task to run as an Amazon ECS task triggered by an EventBridge schedule, eliminating the need for an always-on EC2 instance. Fargate charges only for the vCPU and memory resources consumed during the task's execution (typically 10–45 minutes), which aligns with the team's goal of minimizing operational overhead and paying mainly for actual execution time. Writing results to S3 provides durable, cost-effective storage without managing infrastructure.

Answer

Use a scheduled Amazon EC2 Auto Scaling group that keeps a minimum of one instance running at all times.

Answer

Use AWS Lambda triggered by an EventBridge schedule at 02:00 UTC and write results to S3.

Answer

Use an EMR cluster provisioned daily with manual teardown to ensure the instance is always available before 02:00.

Question 14

A startup runs two EC2-based workloads in the same AWS Region. Its customer-facing API is always on, and its nightly video transcoding fleet can restart jobs from checkpoints if an instance is interrupted. The finance team wants the lowest monthly compute cost without changing the application design. Which two actions should the team take? Select two.

Accepted Answer

Buy a Compute Savings Plan to cover the always-on API baseline usage.. A Compute Savings Plan offers the lowest cost for steady-state workloads like the always-on API by committing to a consistent amount of compute usage (measured in $/hour) across any EC2 instance family, size, or region, providing up to 66% savings compared to On-Demand. Option C is correct because the transcoding fleet can tolerate interruptions (jobs restart from checkpoints), making Spot Instances ideal for up to 90% discount over On-Demand, which directly minimizes compute cost without architectural changes.

Answer

Purchase an All Upfront Reserved Instance for the transcoding fleet only.

Answer

Increase the API instance size so CPU utilization stays below 30 percent.

Answer

Move the API tier to Dedicated Hosts to improve isolation and lower spend.

Question 15

A team runs an Amazon NLB in a VPC with targets registered in multiple Availability Zones (AZs). Their bill shows high inter-AZ data transfer charges. They want to reduce unnecessary cross-AZ traffic costs while still maintaining healthy targets per AZ. What change is most likely to reduce inter-AZ charges?

Accepted Answer

Disable cross-zone load balancing on the NLB so each client is routed to targets in the same AZ when possible.. Disabling cross-zone load balancing on an NLB ensures that each client is routed only to targets within the same Availability Zone as the NLB node that receives the traffic. This eliminates inter-AZ data transfer charges because traffic never leaves the AZ boundary, while still maintaining healthy targets per AZ as each AZ independently handles its own client requests.

Answer

Enable cross-zone load balancing so all targets receive traffic from every AZ.

Answer

Move the NLB to a different Region so traffic is always kept local.

Answer

Replace the NLB with a NAT gateway to reduce data charges between AZs.