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

Question 1

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 architecture review board prefers a managed AWS-native control.

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 the application remains available if one AZ fails. The Auto Scaling group must include subnets in multiple AZs and use health checks (e.g., ELB health checks) to automatically replace unhealthy instances. This configuration meets the requirement for fault tolerance and aligns with AWS-managed best practices for high availability.

Answer

A single EC2 instance with detailed monitoring

Answer

All instances in one larger subnet

Answer

A Network Load Balancer in one subnet

Question 2

A regional web application for a content publishing system must fail over automatically to a secondary Region if the primary endpoint becomes unhealthy. Which two services or features are required? The architecture review board prefers a managed AWS-native control.

Accepted Answer

Route 53 failover routing with health checks. Route 53 failover routing with health checks (Option B) is required because it monitors the primary endpoint's health and automatically reroutes traffic to a secondary Region when the primary becomes unhealthy. This is the managed AWS-native control for DNS-based failover, meeting the architecture review board's preference.

Answer

AWS Organizations service control policies

Answer

S3 Transfer Acceleration

Question 3

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

Accepted Answer

Amazon SQS queue. Amazon SQS is the correct choice because it acts as a fully managed message queue that decouples the web tier from the fulfilment workers, buffering incoming order bursts. It provides at-least-once delivery and allows workers to poll messages at their own pace, ensuring no requests are lost even during spikes. SQS also supports retries via a dead-letter queue (DLQ) for messages that fail processing, meeting the requirement for resilient, managed AWS-native control.

Answer

AWS WAF

Answer

Amazon Route 53 weighted routing

Answer

Amazon CloudFront

Question 4

A payments API uses Amazon SQS. Poison messages are repeatedly failing and blocking useful retries. What should the architect configure? The architecture review board prefers a managed AWS-native control.

Accepted Answer

A dead-letter queue with an appropriate maxReceiveCount. A dead-letter queue (DLQ) with an appropriate maxReceiveCount is the correct AWS-native solution for handling poison messages. When a message is repeatedly received from an SQS queue but fails processing, it is considered a poison message. By configuring a DLQ and setting a maxReceiveCount (e.g., 3 or 5), the message is automatically moved to the DLQ after exceeding that threshold, preventing it from blocking further retries and allowing the main queue to process 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 5

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

Accepted Answer

S3 Cross-Region Replication with versioning enabled. S3 Cross-Region Replication (CRR) is a fully managed AWS-native feature that automatically replicates objects from a source S3 bucket in one AWS Region to a destination bucket in another Region, meeting the disaster recovery requirement for a geographically separate copy. Enabling versioning on both buckets is mandatory for CRR to function, as it tracks object versions and ensures consistency during replication.

Answer

S3 lifecycle transition to Glacier Flexible Retrieval

Answer

An EBS snapshot schedule

Answer

A CloudFront distribution

Question 6

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.

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 7

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 8

A claims workflow requires point-in-time recovery and accidental-delete protection for a DynamoDB table. Which two settings should the architect enable? The architecture review board prefers a managed AWS-native control.

Accepted Answer

Point-in-time recovery. Point-in-time recovery (PITR) for DynamoDB enables continuous backups with 35-day granularity, allowing restoration to any second within that window. This satisfies the point-in-time recovery requirement by providing a managed AWS-native control that automatically backs up table data without manual intervention.

Answer

DAX

Answer

Global secondary indexes

Question 9

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 10

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

Accepted Answer

CloudFront caching with appropriate TTLs. CloudFront caching with appropriate TTLs ensures that even if the S3 origin becomes temporarily unavailable, CloudFront can serve cached content from its edge locations to users. By setting a minimum TTL (e.g., 0 seconds for dynamic content or longer for static assets), CloudFront will continue to serve stale responses from cache during an origin outage, maintaining availability. This is a managed AWS-native feature that requires no additional infrastructure and aligns with the architecture review board's preference.

Answer

IAM Access Analyzer

Answer

AWS Backup Vault Lock

Answer

S3 Select

Question 11

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 12

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? 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 automatically provisions and synchronously replicates a standby instance 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 using the same endpoint). This meets the requirement of remaining available during an AZ failure while being enforceable during normal operations.

Answer

S3 Cross-Region Replication

Answer

Read replicas only

Answer

EBS snapshots every hour

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 team wants the control to be enforceable during normal operations.

Accepted Answer

Subnets in at least two Availability Zones with health checks enabled. Option A is correct because distributing subnets across at least two Availability Zones ensures that if one AZ fails, the Auto Scaling group can launch replacement instances in the remaining AZ(s) to maintain capacity. Enabling health checks on the Application Load Balancer allows the Auto Scaling group to detect and replace unhealthy instances, enforcing resilience during normal operations without manual intervention.

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 team wants the control to be enforceable during normal operations.

Accepted Answer

Route 53 failover routing with health checks. Route 53 failover routing with health checks is correct because it enables automatic DNS-level failover to a secondary Region when the primary endpoint is unhealthy. Route 53 health checks monitor the primary endpoint's health, and if they detect a failure, the DNS record is updated to route traffic to the secondary Region's endpoint. This provides enforceable control during normal operations by allowing you to define routing policies that are active at all times.

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 team wants the control to be enforceable during normal operations.

Accepted Answer

Amazon SQS queue. Amazon SQS is the correct choice because it acts as a durable buffer between the web tier and fulfilment workers, decoupling the producers from consumers. When bursts of orders arrive, SQS queues the messages and allows the fulfilment service to poll and process them at its own pace, absorbing spikes without data loss. The queue provides at-least-once delivery and supports retries via a dead-letter queue, ensuring no requests are lost even if processing fails.

Answer

AWS WAF

Answer

Amazon CloudFront

Answer

Amazon Route 53 weighted routing