SAA-C03 Design Resilient Architectures Practice Test 9 — 15 Questions

Question 1

Based on the exhibit, the business needs Regional disaster recovery with an RTO of 45 minutes and an RPO of 15 minutes. The solution should keep cost lower than running two fully active production environments. Which DR strategy is the best fit?

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

Accepted Answer

Warm standby, because a scaled-down but fully functional copy can take traffic quickly while keeping costs below full duplication.. Warm standby is the best fit because it maintains a scaled-down but fully functional copy of the production environment in the recovery Region, which can be quickly scaled up to handle production traffic. This meets the RTO of 45 minutes and RPO of 15 minutes by keeping the standby environment ready with replicated data (e.g., using Amazon RDS Multi-AZ or cross-Region read replicas with synchronous replication), while costing less than two fully active environments since the standby runs on smaller instances or fewer resources until failover.

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Backup and restore only, because the existing daily backups are already in another Region.

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Pilot light, because the recovery Region only needs minimal resources and can be scaled after a disaster.

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Active-active, because it minimizes RTO by keeping both Regions fully live all the time.

Question 2

Based on the exhibit, some SQS messages fail validation repeatedly and continue consuming worker time. What change best prevents the bad messages from being retried forever?

Accepted Answer

Configure a dead-letter queue and a redrive policy for messages that exceed the retry limit.. A dead-letter queue (DLQ) with a redrive policy allows messages that have been received a maximum number of times (e.g., after the configured retry limit) to be moved to a separate queue for analysis or manual handling. This prevents the same invalid message from being repeatedly processed by workers, freeing up compute resources and avoiding infinite retry loops.

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Increase the visibility timeout so each message has more time to finish processing.

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Replace the queue with an Amazon SNS topic so failed messages will not be retried.

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Increase the number of workers so the queue drains faster during peak load.

Question 3

Based on the exhibit, the web team wants the application to continue serving traffic if one Availability Zone fails. Which change best meets the requirement with the least operational overhead?

Accepted Answer

Add the unused subnet in us-east-1b to the Auto Scaling group so instances can launch in both AZs.. It adds the unused subnet in us-east-1b to the Auto Scaling group, enabling EC2 instances to launch across two Availability Zones. This provides fault isolation: if one AZ fails, the ALB can route traffic to healthy instances in the other AZ. The change requires only a configuration update to the Auto Scaling group, minimizing operational overhead while meeting the high-availability requirement.

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Increase desired capacity to 3 in the same Availability Zone so one extra instance is always available.

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Replace the Application Load Balancer with a Network Load Balancer because it will automatically keep the app online.

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Move the application to a larger EC2 instance type so a single server can handle the full workload.

Question 4

A payments API uses an RDS MySQL database and must remain available during an Availability Zone failure with minimal application changes. What should the architect enable?

Accepted Answer

Multi-AZ deployment for the RDS DB instance. Multi-AZ deployment for RDS MySQL automatically provisions and maintains a synchronous standby replica in a different Availability Zone. In the event of an AZ failure, Amazon RDS automatically fails over to the standby, providing high availability with minimal application changes (the application only needs to reconnect to the same endpoint). This meets the requirement for availability during an AZ outage without requiring code modifications.

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S3 Cross-Region Replication

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Read replicas only

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EBS snapshots every hour

Question 5

A ticket booking system runs on EC2 instances behind an Application Load Balancer. The design must tolerate the failure of one Availability Zone. What should the Auto Scaling group configuration include?

Accepted Answer

Subnets in at least two Availability Zones with health checks enabled. An Auto Scaling group configured with subnets in at least two Availability Zones and health checks enabled ensures that if one AZ fails, EC2 instances in the remaining AZs continue to serve traffic. The Application Load Balancer distributes requests across healthy instances in multiple AZs, and the Auto Scaling group replaces failed instances in the affected AZ, maintaining capacity. This design meets the requirement to tolerate the failure of one Availability Zone.

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All instances in one larger subnet

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A Network Load Balancer in one subnet

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A single EC2 instance with detailed monitoring

Question 6

A regional web application for a inventory service must fail over automatically to a secondary Region if the primary endpoint becomes unhealthy. Which two services or features are required?

Accepted Answer

Route 53 failover routing with health checks. Route 53 failover routing with health checks is correct because it monitors the health of the primary endpoint via periodic HTTP/HTTPS or TCP checks. If the health check fails, Route 53 automatically updates DNS resolution to point to the secondary Region's endpoint, enabling failover at the DNS level without manual intervention.

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S3 Transfer Acceleration

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AWS Organizations service control policies

Question 7

A patient portal receives bursts of orders that sometimes overwhelm a downstream fulfilment service. The architecture must absorb spikes and retry processing without losing requests. Which service should be placed between the web tier and fulfilment workers?

Accepted Answer

Amazon SQS queue. Amazon SQS is the correct choice because it acts as a durable, highly available message buffer between the web tier and the fulfilment workers. It decouples the components, allowing the web tier to enqueue requests immediately without waiting for the downstream service, and the workers can poll and process messages at their own pace. SQS automatically retains messages for up to 14 days and supports retries via a dead-letter queue, ensuring no requests are lost even during spikes.

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AWS WAF

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Amazon CloudFront

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Amazon Route 53 weighted routing

Question 8

A claims workflow uses Amazon SQS. Poison messages are repeatedly failing and blocking useful retries. What should the architect configure?

Accepted Answer

A dead-letter queue with an appropriate maxReceiveCount. A dead-letter queue (DLQ) with an appropriate maxReceiveCount allows messages that repeatedly fail processing to be moved out of the source queue after a specified number of receive attempts. This prevents poison messages from blocking the queue and consuming retry capacity, enabling the workflow to continue processing valid messages without interruption.

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A FIFO queue without a redrive policy

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Short polling instead of long polling

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A larger message retention period only

Question 9

A content publishing system uses Lambda functions that call an unreliable third-party API. Failed events must be retained for later investigation after retries are exhausted. What should be configured?

Accepted Answer

A Lambda dead-letter queue or failure destination. A Lambda dead-letter queue (DLQ) or failure destination captures events that have exhausted all retry attempts, preserving them in Amazon SQS or SNS for later investigation. This ensures failed invocations from the unreliable third-party API are not lost and can be analyzed or replayed, meeting the requirement for retention after retries are exhausted.

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Lambda reserved concurrency set to zero

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A larger deployment package

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CloudFront error pages

Question 10

A warehouse integration service must use shared file storage across Linux EC2 instances in multiple Availability Zones. The storage must remain available during an AZ failure. Which service should be used?

Accepted Answer

Amazon EFS with mount targets in multiple Availability Zones. Amazon EFS provides a fully managed, scalable, and elastic NFS file system that can be mounted concurrently on multiple Linux EC2 instances across different Availability Zones. By configuring mount targets in each AZ, the file system remains accessible even if one AZ fails, because the other mount targets continue to serve traffic. This meets the requirement for shared, highly available file storage across AZs.

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S3 mounted as a POSIX file system without a file gateway

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Instance store volumes

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An EBS volume attached to all instances

Question 11

A payments API requires point-in-time recovery and accidental-delete protection for a DynamoDB table. Which two settings should the architect enable?

Accepted Answer

Deletion protection or tightly controlled delete permissions. Deletion protection (Option A) prevents accidental table deletion by blocking DropTable API calls unless explicitly disabled, which is essential for protecting the payments table from human error or automated scripts. Point-in-time recovery (Option B) enables continuous backups with 35-day granularity, allowing restoration to any second within that window to recover from accidental writes or data corruption. Together, these settings satisfy both the point-in-time recovery and accidental-delete protection requirements for the DynamoDB table.

Answer

Global secondary indexes

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DAX

Question 12

A ticket booking system uses Aurora MySQL. The company wants fast cross-Region disaster recovery with low RPO. Which architecture should be considered?

Accepted Answer

Aurora Global Database. Aurora Global Database is designed for cross-Region disaster recovery with a typical RPO of 1 second or less, using storage-based replication that does not impact database performance. This meets the requirement for fast failover and low data loss, unlike manual snapshot-based approaches which have higher RPO and slower recovery.

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A single-AZ Aurora cluster

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An ElastiCache Redis replica

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Manual snapshots copied monthly

Question 13

A inventory service exposes a static website from S3 and CloudFront. Users should still receive cached pages if the S3 origin has a short outage. Which feature helps most?

Accepted Answer

CloudFront caching with appropriate TTLs. CloudFront caches responses from the S3 origin based on configured TTLs (Cache-Control or Expires headers). If the S3 origin experiences a short outage, CloudFront can still serve cached pages to users from its edge locations, maintaining availability. This is the most direct way to ensure users receive content during origin failures.

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AWS Backup Vault Lock

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IAM Access Analyzer

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S3 Select

Question 14

A patient portal must process every event at least once, but duplicate processing is acceptable if the consumer handles idempotency. Which eventing approach is most suitable?

Accepted Answer

Use Amazon SQS standard queue and design consumers to be idempotent. Amazon SQS standard queues provide at-least-once delivery, meaning each message is delivered at least once but may occasionally be delivered more than once. This aligns with the requirement that every event must be processed at least once, and since duplicate processing is acceptable when consumers are idempotent, the standard queue is the most suitable choice. SQS handles the decoupling and durability of messages without requiring custom infrastructure.

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Use an in-memory queue on one EC2 instance

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Use UDP messages sent directly to workers

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Use CloudFront signed URLs

Question 15

A trading dashboard runs on EC2 instances behind an Application Load Balancer. The design must tolerate the failure of one Availability Zone. What should the Auto Scaling group configuration include?

Accepted Answer

Subnets in at least two Availability Zones with health checks enabled. Distributing EC2 instances across subnets in at least two Availability Zones ensures that if one AZ fails, the Auto Scaling group can maintain capacity using instances in the remaining AZ(s). Enabling health checks allows the group to detect and replace unhealthy instances, which is essential for fault tolerance. This configuration meets the requirement to tolerate the failure of one Availability Zone.

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A single EC2 instance with detailed monitoring

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All instances in one larger subnet

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A Network Load Balancer in one subnet