SAA-C03 Design Resilient Architectures Practice Test 14 — 15 Questions

Question 1

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?

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

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 2

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 3

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.. The provided explanation for deploying EC2 instances across AZs is accurate and correctly justifies that design choice. However, the overall question structure is flawed due to the contradiction between the stem and one of the marked correct options regarding 'improvement'.

Answer

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

Answer

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

Answer

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

Question 4

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 SQS for asynchronous message passing between application components.. 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. Amazon SNS is correct because it facilitates event-driven architectures by allowing components to publish events to topics, which are then fanned out to multiple subscribers. This further decouples components as publishers do not need to know about specific subscribers, enhancing resilience and scalability. AWS Lambda is correct because it allows components to be re-architected as stateless, serverless functions. This inherently promotes decoupling by removing state dependencies between instances and provides automatic scaling and high availability, significantly improving the overall resilience and agility of the application.

Answer

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

Answer

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

Answer

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

Question 5

A company runs a production database on Amazon RDS for MySQL with Multi-AZ enabled. The database experiences a sudden increase in read replicas due to a marketing campaign. Which three strategies would help ensure the database remains resilient under heavy read traffic? (Choose three.)

Accepted Answer

Create additional read replicas in different Availability Zones to distribute read traffic.. Creating additional read replicas in different Availability Zones distributes read traffic across multiple isolated locations, reducing load on the primary instance and improving read scalability. Using RDS Proxy between the application and the database manages connection pooling, which reduces the number of database connections and prevents resource exhaustion under heavy traffic. Configuring the application to use the read replica endpoint for read queries and the primary endpoint for writes offloads read traffic from the primary instance, preserving its capacity for write operations and maintaining write availability.

Answer

Promote a read replica to a standalone DB instance to offload write traffic.

Answer

Enable Multi-AZ on the read replicas to provide automatic failover for read operations.

Answer

Increase the storage size of the primary DB instance to improve I/O throughput.

Question 6

A company is designing a multi-tier web application on AWS that must be resilient to the failure of an entire AWS Region. The application uses Amazon Route 53, an Application Load Balancer, EC2 instances, and Amazon RDS. Which three design choices support a multi-Region resilient architecture? (Choose three.)

Accepted Answer

Configure Route 53 with a failover routing policy and health checks on the application endpoints.. Options C, E, and F are correct. Option C (Configure Route 53 with a failover routing policy and health checks) allows DNS to automatically route traffic away from a failed primary region to a standby region, essential for multi-Region resilience. Option E (Deploy the application stack in two separate AWS Regions with an active-passive setup) ensures regional fault isolation. Option F (Use Amazon RDS Cross-Region read replicas) keeps the standby region's database synchronized, enabling promotion in a disaster recovery scenario. The other options do not provide regional failover capability.

Answer

Use Route 53 latency-based routing to direct users to the closest healthy region.

Answer

Store all application state in a single Amazon ElastiCache cluster in the primary region.

Answer

Place the Application Load Balancer in a single region but use it across multiple Availability Zones.

Question 7

Order the steps for setting up a VPC with public and private subnets using a NAT gateway.

Accepted Answer

Create VPC, Create public and private subnets, Create and attach Internet Gateway, Create NAT Gateway, Update route tables for public and private subnets. VPC creation comes first, then subnets, IGW, NAT Gateway, and finally route table updates.

Answer

Create VPC, Create public and private subnets, Create NAT Gateway, Create and attach Internet Gateway, Update route tables for public and private subnets

Answer

Create VPC, Create and attach Internet Gateway, Create NAT Gateway, Create public and private subnets, Update route tables for public and private subnets

Answer

Create VPC, Create public and private subnets, Update route tables for public and private subnets, Create and attach Internet Gateway, Create NAT Gateway

Question 8

Order the steps to restore an Amazon RDS DB instance from a snapshot.

Accepted Answer

Choose the snapshot, then restore to a new DB instance, then configure the new instance (security groups, parameter groups, etc.), then redirect application traffic to the new instance, then delete the old DB instance.. The correct order for restoring an Amazon RDS DB instance from a snapshot is: first, choose the snapshot to restore from; second, restore the snapshot to a new DB instance; third, configure the new instance (e.g., security groups, parameter groups, and any other settings); fourth, redirect application traffic to the new instance; and finally, delete the old DB instance. This sequence ensures minimal downtime and data integrity.

Answer

Restore to a new DB instance, then configure the new instance, then choose the snapshot, then redirect application traffic, then delete the old DB instance.

Answer

Choose the snapshot, then restore to a new DB instance, then delete the old DB instance, then configure the new instance, then redirect application traffic.

Answer

Choose the snapshot, then restore to a new DB instance, then redirect application traffic, then configure the new instance, then delete the old DB instance.

Question 9

A payments platform requires disaster recovery across Regions. Requirements: RPO of 15 minutes and RTO of about 1 hour. The business cannot afford full duplicate capacity in both Regions all the time, but the team wants automated readiness so failover is mostly operationally guided rather than a slow rebuild. Which DR strategy is the best fit?

Accepted Answer

Warm standby, keeping core infrastructure and a partially provisioned environment ready in the secondary Region with frequent data replication.. Warm standby is the best fit because it maintains a partially provisioned environment in the secondary Region with core infrastructure (e.g., a smaller EC2 Auto Scaling group, a standby database with synchronous or asynchronous replication) and frequent data replication, enabling an RPO of 15 minutes and an RTO of about 1 hour. This approach balances cost and automated readiness, as the team can scale up the standby environment during failover without the expense of full duplicate capacity, while still meeting the recovery objectives through automated replication (e.g., Amazon RDS Multi-AZ cross-Region or DynamoDB global tables).

Answer

Backup and restore only, relying on scheduled snapshots and manual restores during incidents.

Answer

Pilot light, keeping only minimal infrastructure in the secondary Region and starting full services after failover.

Answer

Active/active, routing production traffic to both Regions continuously and accepting dual-region complexity.

Question 10

Match the disaster recovery strategy to the recovery posture it best fits for a Regional outage.

Accepted Answer

Backup & Restore: RPO hours, RTO 24+ hours. These pairs match disaster recovery strategies to their recovery postures, aligning with AWS DR strategies where RTO and RPO define the recovery objectives.

Answer

Backup & Restore: RPO seconds, RTO minutes

Answer

Multi-Site Active/Active: RPO hours, RTO 24+ hours

Question 11

Based on the exhibit, the database must fail over automatically if the primary Availability Zone goes down. Which solution should the architect choose?

Accepted Answer

Convert the database to a Multi-AZ RDS deployment.. A Multi-AZ RDS deployment automatically synchronously replicates data to a standby instance in a different Availability Zone. If the primary AZ fails, Amazon RDS automatically performs a failover to the standby, ensuring high availability without manual intervention. This meets the requirement for automatic failover when the primary AZ goes down.

Answer

Create a read replica in the same Availability Zone as the primary database.

Answer

Increase the backup retention period to 35 days.

Answer

Move the database to an EC2 instance with an attached EBS volume.

Question 12

A stateless web API runs on EC2 instances behind an Application Load Balancer (ALB). The Auto Scaling group (ASG) currently uses subnets from only one Availability Zone, even though the ALB spans two Availability Zones. During maintenance of that single AZ, the ALB remains up but clients see timeouts because there are no healthy targets. Which change most directly improves resilience against an AZ failure?

Accepted Answer

Update the ASG to launch instances across subnets in at least two Availability Zones and ensure ALB health checks target an application-ready path.. The most direct fix for AZ failure resilience is to distribute the ASG across multiple Availability Zones. With the ALB already spanning two AZs, if the ASG only launches instances in one AZ, a failure of that AZ leaves the ALB with zero healthy targets, causing timeouts. By configuring the ASG to launch instances in at least two AZs and setting ALB health checks to an application-ready path, the ALB can route traffic to healthy instances in the surviving AZ, maintaining availability.

Answer

Keep the ASG in one subnet/AZ, but enable ALB stickiness to reduce session interruption.

Answer

Add a NAT gateway in the public subnets so instances can reach the internet during maintenance events.

Answer

Create a second ALB in the same Availability Zone and route traffic using DNS failover.

Question 13

A caching layer uses Amazon ElastiCache for Redis in front of a stateless web service. The service must continue to read cached responses during maintenance events and should automatically fail over to another node if one AZ becomes impaired. Which design change best satisfies this requirement?

Accepted Answer

Configure an ElastiCache Redis replication group with automatic failover across multiple Availability Zones.. An ElastiCache Redis replication group with automatic failover across multiple Availability Zones ensures that if the primary node or its AZ becomes impaired, a read-replica in another AZ is automatically promoted to primary. This allows the stateless web service to continue reading cached responses without interruption, satisfying both the maintenance and AZ impairment requirements.

Answer

Deploy a single-node Redis cluster and rely on application-level retries when cache misses occur.

Answer

Move the cache into the VPC but keep it in one Availability Zone to reduce network latency.

Answer

Use a Memcached cluster and configure only client-side connection pooling without failover support.

Question 14

A company runs a stateful analytics workload on EC2 instances that use EBS volumes. The data must be restorable in another Region after a major outage, with frequent point-in-time recovery. Which approach provides the most suitable replication mechanism for the EBS-backed data?

Accepted Answer

Create scheduled EBS snapshots and copy them to another Region, then restore the volumes from those snapshots during recovery.. Scheduled EBS snapshots provide point-in-time backups of EBS volumes, which can be copied to another Region using the cross-Region snapshot copy feature. During recovery, you restore volumes from those snapshots in the target Region, ensuring the data is restorable after a major outage. This approach meets the requirements for frequent point-in-time recovery and cross-Region durability.

Answer

Enable EBS multi-attach to spread the workload across AZs and replicate snapshots automatically between Regions.

Answer

Use RDS read replicas in another Region and keep the analytics dataset in an RDS instance only.

Answer

Rely on instance store for durability and copy only AMIs across Regions.

Question 15

Your order-processing system uses EventBridge rules to send events to a Lambda function that updates order status. Over the last week, some events fail with a transient database timeout, and the Lambda retries intermittently but then the events are lost (no alerts after failures). You want at-least-once processing, bounded retries, and a way to inspect unprocessable events for later reprocessing.

Which architecture change best meets these requirements?

Accepted Answer

Send EventBridge events to an SQS queue, configure a redrive policy to move messages to a dead-letter queue (DLQ) after a defined receive count, and make the Lambda processing idempotent.. It introduces an SQS queue between EventBridge and Lambda, which provides a durable buffer for events. The redrive policy moves events to a dead-letter queue (DLQ) after a defined number of failed processing attempts, ensuring bounded retries and preserving unprocessable events for later inspection and reprocessing. Making the Lambda idempotent guarantees at-least-once processing even if duplicate events occur.

Answer

Invoke Lambda directly from EventBridge in asynchronous mode, and increase the Lambda timeout to reduce failures.

Answer

Use SNS topics with Lambda subscriptions, but remove all retry and DLQ configuration to minimize duplicate events.

Answer

Store failed events only in CloudWatch logs, and have operators manually copy log entries back into the database for reprocessing.