SAA-C03 Design Resilient Architectures Practice Test 19 — 15 Questions

Question 1

A inventory service 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? The architecture review board prefers a managed AWS-native control.

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

Accepted Answer

A Lambda dead-letter queue or failure destination. Lambda dead-letter queues (DLQs) or failure destinations are the correct AWS-native mechanism to retain failed events after retries are exhausted. When a Lambda function fails to process an event (e.g., due to an unreliable third-party API), the function can be configured to send the failed event payload to an SQS queue or SNS topic for later investigation. This ensures no data loss and aligns with the requirement for a managed, AWS-native solution.

Answer

Lambda reserved concurrency set to zero

Answer

A larger deployment package

Answer

CloudFront error pages

Question 2

A patient portal 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? The architecture review board prefers a managed AWS-native control.

Accepted Answer

Amazon EFS with mount targets in multiple Availability Zones. Amazon EFS provides a fully managed, shared POSIX-compliant file system that can be mounted concurrently across multiple Linux EC2 instances. By creating mount targets in multiple Availability Zones, the file system remains accessible even if one AZ fails, meeting the high-availability requirement. This aligns with the architecture review board's preference for a managed AWS-native control.

Answer

Instance store volumes

Answer

An EBS volume attached to all instances

Answer

S3 mounted as a POSIX file system without a file gateway

Question 3

A trading dashboard uses Aurora MySQL. The company wants fast cross-Region disaster recovery with low RPO. Which architecture should be considered? The architecture review board prefers a managed AWS-native control.

Accepted Answer

Aurora Global Database. Aurora Global Database is the correct choice because it provides a managed, cross-Region disaster recovery solution with a Recovery Point Objective (RPO) of less than 1 second and a Recovery Time Objective (RTO) of typically less than 1 minute. It uses storage-based replication to keep a secondary cluster in another AWS Region up to date with minimal latency, meeting the low RPO requirement without manual intervention.

Answer

A single-AZ Aurora cluster

Answer

Manual snapshots copied monthly

Answer

An ElastiCache Redis replica

Question 4

A warehouse integration service must process every event at least once, but duplicate processing is acceptable if the consumer handles idempotency. Which eventing approach is most suitable? The architecture review board prefers a managed AWS-native control.

Accepted Answer

Use Amazon SQS standard queue and design consumers to be idempotent. Amazon SQS standard queues provide at-least-once delivery, which guarantees that every message is processed at least once, meeting the requirement that every event must be processed. Duplicate processing is acceptable because the consumer can be designed to handle idempotency. This is a managed, AWS-native service that aligns with the architecture review board's preference.

Answer

Use CloudFront signed URLs

Answer

Use UDP messages sent directly to workers

Answer

Use an in-memory queue on one EC2 instance

Question 5

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? The team wants the control to be enforceable during normal operations.

Accepted Answer

Route 53 failover routing with health checks. Option A (Route 53 failover routing with health checks) is correct because Route 53 failover routing policies use health checks on the primary endpoint; when the health check reports the primary as unhealthy, Route 53 automatically returns the secondary Region's record, providing the required automatic DNS-level failover. Option C (a deployed standby application stack in the secondary Region) is correct because failover routing can only redirect traffic to a target that actually exists and can serve requests, so a running standby stack (for example, on EC2, ECS, or Elastic Beanstalk) must already be deployed in the secondary Region for the failover to succeed. Option B (S3 Transfer Acceleration) is incorrect because it only speeds up uploads/downloads to S3 buckets using edge locations and does not provide health-check-based regional failover for a web application. Option D (AWS Organizations service control policies) is incorrect because SCPs only set permission guardrails for accounts in an organization and cannot detect an unhealthy endpoint or redirect traffic between Regions.

Answer

S3 Transfer Acceleration

Answer

AWS Organizations service control policies

Question 6

A claims workflow uses Amazon SQS. Poison messages are repeatedly failing and blocking useful retries. What should the architect configure? The team wants the control to be enforceable during normal operations.

Accepted Answer

A dead-letter queue with an appropriate maxReceiveCount. A dead-letter queue (DLQ) with an appropriate maxReceiveCount is the correct solution because it automatically moves messages that have failed processing a specified number of times to a separate queue, preventing them from blocking subsequent retries. This enforces control during normal operations by isolating poison messages without manual intervention, allowing the main queue to continue processing valid messages.

Answer

A FIFO queue without a redrive policy

Answer

Short polling instead of long polling

Answer

A larger message retention period only

Question 7

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? The team wants the control to be enforceable during normal operations.

Accepted Answer

A Lambda dead-letter queue or failure destination. A Lambda dead-letter queue (DLQ) or failure destination allows you to capture events that have exhausted all retry attempts from an asynchronous invocation. This ensures failed events are retained in Amazon SQS or SNS for later investigation, providing enforceable control during normal operations without impacting the function's ability to process successful events.

Answer

Lambda reserved concurrency set to zero

Answer

A larger deployment package

Answer

CloudFront error pages

Question 8

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? The team wants the control to be enforceable during normal operations.

Accepted Answer

Amazon EFS with mount targets in multiple Availability Zones. Amazon EFS provides a fully managed, POSIX-compliant NFS file system that can be mounted concurrently on multiple Linux EC2 instances across different Availability Zones. By creating mount targets in each AZ, the file system remains accessible even if one AZ fails, because the other mount targets continue to serve traffic. EFS also supports lifecycle policies and IAM enforcement to control access during normal operations, meeting the requirement for enforceable control.

Answer

S3 mounted as a POSIX file system without a file gateway

Answer

Instance store volumes

Answer

An EBS volume attached to all instances

Question 9

A payments API requires point-in-time recovery and accidental-delete protection for a DynamoDB table. Which two settings should the architect enable? The team wants the control to be enforceable during normal operations.

Accepted Answer

Deletion protection or tightly controlled delete permissions. Deletion protection (Option A) prevents accidental table deletion by blocking drop-table operations, which is enforceable during normal operations. Point-in-time recovery (Option B) enables continuous backups with 35-day granularity, allowing restoration to any second within that window. Together, they satisfy the requirements for accidental-delete protection and point-in-time recovery.

Answer

Global secondary indexes

Answer

DAX

Question 10

A ticket booking system uses Aurora MySQL. The company wants fast cross-Region disaster recovery with low RPO. Which architecture should be considered? The team wants the control to be enforceable during normal operations.

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. It provides fast failover to a secondary Region and allows the primary Region to enforce write control during normal operations, meeting the low RPO and enforceable control requirements.

Answer

A single-AZ Aurora cluster

Answer

An ElastiCache Redis replica

Answer

Manual snapshots copied monthly

Question 11

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? The team wants the control to be enforceable during normal operations.

Accepted Answer

Use Amazon SQS standard queue and design consumers to be idempotent. Amazon SQS standard queues provide at-least-once delivery, ensuring every event is processed at least once, which matches the requirement. Duplicate processing is acceptable because the team can design consumers to be idempotent, handling duplicates without side effects. SQS is a fully managed, scalable, and durable service that enforces this behavior during normal operations without requiring custom infrastructure.

Answer

Use an in-memory queue on one EC2 instance

Answer

Use UDP messages sent directly to workers

Answer

Use CloudFront signed URLs

Question 12

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? The team wants the control to be enforceable during normal operations.

Accepted Answer

Subnets in at least two Availability Zones with health checks enabled. Distributing EC2 instances across at least two Availability Zones (AZs) ensures that if one AZ fails, the Auto Scaling group can maintain capacity in the remaining AZ(s). Enabling health checks allows the group to detect instance failures and automatically replace them, providing fault tolerance. This configuration meets the requirement to tolerate a single AZ failure while remaining enforceable during normal operations.

Answer

A single EC2 instance with detailed monitoring

Answer

All instances in one larger subnet

Answer

A Network Load Balancer in one subnet

Question 13

A company runs a production MySQL database on Amazon RDS in us-east-1. A read replica exists in us-west-2 for disaster recovery. The primary region experiences a complete outage. Which of the following describes the correct procedure to restore database service using the cross-region read replica?

Accepted Answer

Manually promote the us-west-2 read replica to a standalone DB instance and update application endpoints. Cross-region RDS read replicas support manual promotion to a standalone database instance. When the primary region fails, the replica must be manually promoted — this makes it an independent writable instance in us-west-2.

Key points: Promotion is NOT automatic (unlike RDS Multi-AZ failover). Promotion breaks the replication link — the replica becomes autonomous. After promotion, application connection strings must be updated to the new endpoint. Any replication lag at the time of the outage represents potential data loss (RPO > 0).

Answer

Wait for AWS to automatically fail over the read replica to become the new primary

Answer

Restore the primary database from the most recent automated snapshot in us-west-2

Answer

Create a new RDS instance in us-west-2 and manually restore data from application logs

Question 14

A company hosts a web application on EC2 instances behind an Application Load Balancer (ALB) in us-east-1. A static failover site is hosted in an S3 bucket with static website hosting enabled. The company needs automatic DNS failover to the S3 bucket if the primary ALB becomes unhealthy. Which Route 53 configuration achieves this?

Accepted Answer

Configure Route 53 Failover routing with a health check on the ALB as PRIMARY and the S3 bucket website endpoint as SECONDARY. Route 53 Failover routing uses health checks to route traffic to a primary resource and automatically switch to a secondary when the primary health check fails.

Configuration: Create a Route 53 health check targeting the ALB endpoint. Create a PRIMARY alias A record pointing to the ALB with the health check associated. Create a SECONDARY alias A record pointing to the S3 static website endpoint. When the ALB health check fails, Route 53 returns the S3 endpoint automatically.

Answer

Configure Route 53 Weighted routing with 100% weight on the ALB and 0% on the S3 bucket

Answer

Configure Route 53 Latency routing with records in both regions to route to the healthiest endpoint

Answer

Configure Route 53 Geolocation routing with North American users directed to the ALB and all others to S3

Question 15

A company is deploying a stateless web application on Amazon ECS with Fargate. The application must be resilient to individual task failures and Availability Zone failures. Which three steps should the company take to achieve this resilience? (Choose three.)

Accepted Answer

Configure the ECS service to use a spread placement strategy across Availability Zones.. Configuring the ECS service with a spread placement strategy across Availability Zones ensures tasks are distributed across multiple AZs, providing resilience against AZ failures. Setting a minimum healthy percent of 50 and a maximum percent of 200 allows the service to maintain at least half of the desired tasks during deployments or failures while scaling up to replace failed tasks without downtime. Using an Application Load Balancer (ALB) in front of the ECS service distributes incoming traffic across healthy tasks in different AZs, automatically rerouting traffic if a task or AZ fails.

Answer

Disable automatic task replacement to avoid unnecessary task churn during failures.

Answer

Place all ECS tasks in a single subnet to minimize network latency.

Answer

Store application session data in an attached EFS file system shared across all tasks.