SAA-C03 Design Resilient Architectures Practice Test 16 — 15 Questions

Question 1

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.

Answer

AWS Backup Vault Lock

Answer

IAM Access Analyzer

Answer

S3 Select

Question 2

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.

Answer

Use an in-memory queue on one EC2 instance

Answer

Use UDP messages sent directly to workers

Answer

Use CloudFront signed URLs

Question 3

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?

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 simply reconnects to the same endpoint). This meets the requirement for availability during an AZ outage without requiring code modifications.

Answer

S3 Cross-Region Replication

Answer

EBS snapshots every hour

Answer

Read replicas only

Question 4

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.

Answer

A single EC2 instance with detailed monitoring

Answer

All instances in one larger subnet

Answer

A Network Load Balancer in one subnet

Question 5

A warehouse integration service 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, fully managed message queue that decouples the web tier from the fulfilment workers. It can absorb bursts of orders by storing messages durably, and workers can poll the queue at their own pace, with built-in retry logic via visibility timeouts and dead-letter queues to ensure no requests are lost.

Answer

AWS WAF

Answer

Amazon Route 53 weighted routing

Answer

Amazon CloudFront

Question 6

A payments API 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. B is correct because a dead-letter queue (DLQ) with an appropriate maxReceiveCount allows the payments API to isolate poison messages after a specified number of failed processing attempts. This prevents repeated failures from blocking useful retries, as the problematic messages are moved to the DLQ for manual inspection or separate handling, while the main queue continues processing valid messages.

Answer

A FIFO queue without a redrive policy

Answer

A larger message retention period only

Answer

Short polling instead of long polling

Question 7

A ticket booking system stores uploaded documents in S3. The business requires a copy in another AWS Region for disaster recovery. What should be configured?

Accepted Answer

S3 Cross-Region Replication with versioning enabled. S3 Cross-Region Replication (CRR) with versioning enabled automatically copies objects from a source bucket in one AWS Region to a destination bucket in another Region, meeting the disaster recovery requirement for a geographically separate copy. Versioning must be enabled on both buckets to support replication of all object versions, ensuring consistency and recoverability. This is the native S3 feature designed for cross-region data redundancy without custom scripting or third-party tools.

Answer

S3 lifecycle transition to Glacier Flexible Retrieval

Answer

An EBS snapshot schedule

Answer

A CloudFront distribution

Question 8

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?

Accepted Answer

A Lambda dead-letter queue or failure destination. Lambda dead-letter queues (DLQs) or failure destinations are the correct mechanism to retain failed events after all retries are exhausted. When a Lambda function fails to process an event (e.g., from an asynchronous invocation), the service automatically retries twice. If those retries fail, the event can be sent to an SQS queue or SNS topic (DLQ) or to a specified destination (failure destination) for later investigation. This ensures no data loss and provides a durable storage for post-mortem analysis.

Answer

Lambda reserved concurrency set to zero

Answer

A larger deployment package

Answer

CloudFront error pages

Question 9

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?

Accepted Answer

Amazon EFS with mount targets in multiple Availability Zones. Amazon EFS provides a scalable, fully managed NFS file system that can be mounted concurrently on multiple Linux EC2 instances. By creating mount targets in multiple Availability Zones, the file system remains accessible even if one AZ fails, ensuring high availability and shared file storage across instances.

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 10

A trading dashboard 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 and RTO of less than 1 minute, using storage-based replication that does not impact database performance. This meets the low RPO requirement for a trading dashboard, where data loss must be minimized.

Answer

A single-AZ Aurora cluster

Answer

Manual snapshots copied monthly

Answer

An ElastiCache Redis replica

Question 11

A content publishing system 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 content to users until the TTL expires, maintaining availability. This is the most direct way to ensure users receive pages during transient origin failures.

Answer

IAM Access Analyzer

Answer

AWS Backup Vault Lock

Answer

S3 Select

Question 12

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?

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 can occasionally be delivered more than once. This matches the requirement to process every event at least once, and since duplicate processing is acceptable when consumers are idempotent, the standard queue is the most suitable and cost-effective choice. SQS also decouples the warehouse integration service from its consumers, improving resilience and scalability.

Answer

Use CloudFront signed URLs

Answer

Use UDP messages sent directly to workers

Answer

Use an in-memory queue on one EC2 instance

Question 13

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? The design must avoid adding custom operational scripts.

Accepted Answer

Subnets in at least two Availability Zones with health checks enabled. Placing subnets in at least two Availability Zones ensures that if one AZ fails, the Auto Scaling group can launch instances in the remaining healthy AZ, maintaining application availability. Health checks integrated with the Application Load Balancer allow the Auto Scaling group to automatically replace unhealthy instances without custom scripts, aligning with the requirement to avoid operational overhead.

Answer

All instances in one larger subnet

Answer

A Network Load Balancer in one subnet

Answer

A single EC2 instance with detailed monitoring

Question 14

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 design must avoid adding custom operational scripts.

Accepted Answer

Route 53 failover routing with health checks. Route 53 failover routing with health checks (Option A) is required because it automatically evaluates the health of the primary endpoint and, upon detecting failure, updates DNS resolution to direct traffic to the secondary Region. This is the native AWS mechanism for DNS-based failover without custom scripts, relying on Route 53 health checkers to assess endpoint health via HTTP/HTTPS/TCP or calculated health checks.

Answer

S3 Transfer Acceleration

Answer

AWS Organizations service control policies

Question 15

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? The design must avoid adding custom operational scripts.

Accepted Answer

Amazon SQS queue. Amazon SQS is the correct choice because it acts as a durable, fully managed message buffer that decouples the web tier from the fulfilment workers. When bursts of orders arrive, SQS queues the messages and allows workers to poll at their own pace, absorbing spikes without data loss. The built-in retry logic (visibility timeout and dead-letter queue) ensures failed processing attempts are automatically retried, and no custom operational scripts are needed.

Answer

AWS WAF

Answer

Amazon CloudFront

Answer

Amazon Route 53 weighted routing