SAA-C03 Design Resilient Architectures Practice Test 17 — 15 Questions

Question 1

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 2

A trading dashboard stores uploaded documents in S3. The business requires a copy in another AWS Region for disaster recovery. What should be configured? The team wants the control to be enforceable during normal operations.

Accepted Answer

S3 Cross-Region Replication with versioning enabled. S3 Cross-Region Replication (CRR) automatically replicates objects to a destination bucket in a different AWS Region, providing a disaster recovery copy. Enabling versioning on both source and destination buckets is required for CRR to function, and replication can be enforced during normal operations by applying an IAM policy that denies `s3:PutObject` unless the request includes the `x-amz-server-side-encryption` header or by using a bucket policy that requires replication. This meets the business requirement for an enforceable, automated DR copy.

Answer

An EBS snapshot schedule

Answer

S3 lifecycle transition to Glacier Flexible Retrieval

Answer

A CloudFront distribution

Question 3

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. Option D is correct because 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 4

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 5

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 6

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 7

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

Accepted Answer

CloudFront caching with appropriate TTLs. CloudFront caching with appropriate TTLs allows the distribution to serve stale or cached content from edge locations even when the S3 origin is temporarily unavailable. By setting a minimum TTL (e.g., 0 seconds) and a default/max TTL (e.g., 86400 seconds), CloudFront can continue to respond to user requests with previously cached objects during an origin outage, ensuring high availability. This feature is enforceable during normal operations because the TTL settings are configured in the CloudFront distribution behavior and are always active, not just during failures.

Answer

AWS Backup Vault Lock

Answer

IAM Access Analyzer

Answer

S3 Select

Question 8

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 9

A claims workflow uses an RDS MySQL database and must remain available during an Availability Zone failure with minimal application changes. What should the architect enable? The team wants the control to be enforceable during normal operations.

Accepted Answer

Multi-AZ deployment for the RDS DB instance. Multi-AZ deployment for RDS MySQL provides synchronous standby replication across two Availability Zones. In the event of an AZ failure, Amazon RDS automatically fails over to the standby in the other AZ, ensuring availability with minimal application changes (the same database endpoint is used). This meets the requirement for enforceability during normal operations because Multi-AZ is always active, not a manual or scheduled process.

Answer

S3 Cross-Region Replication

Answer

EBS snapshots every hour

Answer

Read replicas only

Question 10

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. Option B is correct because 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 11

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 12

A company uses Amazon SQS and AWS Lambda to process orders. Lambda typically completes in 4 minutes, but complex orders can take up to 12 minutes. The team reports that some orders are being processed more than once. Which is the MOST likely cause and the recommended fix?

Accepted Answer

Increase the SQS queue visibility timeout to exceed the maximum Lambda processing time. SQS visibility timeout defines how long a message is hidden from other consumers after it is received. If a Lambda function takes longer than the visibility timeout to process a message, the message becomes visible again and another Lambda invocation picks it up — causing duplicate processing.

The default SQS visibility timeout is 30 seconds. If processing takes 12 minutes but visibility timeout is 30 seconds, messages reappear and are processed again. The fix is to increase the visibility timeout to exceed the maximum processing time — at least 13-15 minutes.

Answer

Enable SQS FIFO queue to prevent duplicate message delivery

Answer

Reduce the Lambda function timeout to 4 minutes to match typical processing time

Answer

Enable SQS long polling to reduce the frequency of message retrieval

Question 13

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 14

A company is designing a highly available web application on AWS. The application runs on Amazon EC2 instances behind an Application Load Balancer (ALB) and uses an Amazon RDS Multi-AZ DB instance. Which three design choices would improve the application's resilience against an AWS Availability Zone failure? (Choose three.)

Accepted Answer

Deploy EC2 instances across at least two Availability Zones in the same AWS Region.. Deploying EC2 instances across at least two Availability Zones (AZs) ensures that if one AZ fails, the ALB can route traffic to healthy instances in the other AZ, maintaining application availability. This is a fundamental pattern for building resilient architectures on AWS, as it eliminates the single point of failure at the AZ level.

Answer

Configure the ALB as a Network Load Balancer for faster failover.

Answer

Use Amazon Route 53 health checks with a failover routing policy to redirect traffic to a different Region.

Answer

Provision EC2 instances in a single Availability Zone and use Auto Scaling to replace failed instances.

Question 15

A company is migrating a legacy monolithic application to AWS and wants to improve its resilience by decoupling components. The application currently writes directly to a shared file system and uses synchronous HTTP calls between modules. Which three AWS services should the company use to achieve a more resilient, decoupled architecture? (Choose three.)

Accepted Answer

Amazon SNS to fan-out notifications to multiple subscribers for event-driven processing.. Amazon SQS is correct because it enables asynchronous message passing between application components, decoupling them so that a failure in one component does not block others. This replaces the synchronous HTTP calls, improving resilience by allowing messages to be buffered and processed independently.

Answer

AWS Direct Connect to provide a dedicated network link for inter-component communication.

Answer

Amazon Elastic Block Store (EBS) with Multi-Attach for shared block storage between components.

Answer

Amazon EFS as a shared file system to replace the on-premises NAS.