SAA-C03 Design Resilient Architectures Practice Test 7 — 15 Questions

Question 1

A healthcare company runs a stateless containerized API on Amazon ECS with tasks spread across three Availability Zones in a single Region. Compliance requires the API to remain available if one entire Availability Zone fails, and recovery must occur without manual intervention. The tasks are behind an Application Load Balancer and use an Amazon EFS file system for shared configuration. Which change should the architect make to meet the requirement?

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

Accepted Answer

Configure the ECS service with a desired count of at least two tasks and use the spread placement strategy across Availability Zones, and mount EFS with a mount target in each Availability Zone.. The resilient design spreads ECS tasks across multiple Availability Zones with a desired count greater than one so that an AZ failure leaves healthy tasks. Because the tasks share configuration on Amazon EFS, mount targets must exist in each AZ to allow surviving tasks to mount the file system. Together these provide automatic recovery without manual intervention.

Answer

Increase the ECS task CPU and memory reservation and enable ECS managed scaling with a target tracking policy on CPU utilization.

Answer

Move the tasks to an EC2 Auto Scaling group with a launch template that spans all Availability Zones and attach the group to the existing Application Load Balancer.

Answer

Enable ECS service auto scaling based on the ALB request count per target and set the minimum task count to one in each of two Availability Zones.

Question 2

A retail company hosts a product catalog on an Amazon RDS for MySQL Multi-AZ DB instance. During a maintenance window, AWS performs a failover and the application experiences about 90 seconds of failed database connections. The application team wants the connection string to recover automatically without code changes. Which action should a solutions architect take?

Accepted Answer

Configure the application to connect using the RDS cluster endpoint, which resolves to the current primary after failover.. RDS maintains a cluster endpoint whose DNS record is repointed to the promoted standby when a Multi-AZ DB instance fails over. Clients that reconnect to that name reach the new primary without configuration changes, and adding standard connection retry logic bridges the brief window while DNS propagates. This is the intended way to make failover transparent to an application.

Answer

Create an Amazon Route 53 latency-based record that targets the standby instance and let the application resolve it.

Answer

Use the RDS DB instance's CNAME and increase the client's TCP keepalive timeout to survive the failover.

Answer

Point the application at the RDS instance endpoint rather than the cluster endpoint and rely on DNS caching.

Question 3

A logistics company runs an order-processing application that writes events to an Amazon Kinesis Data Streams stream with two shards. During peak season, the application experiences ProvisionedThroughputExceededException errors and some events are lost because producers do not retry. The company wants to improve durability and throughput without changing the producer application code. Which two actions should the architect take? (Choose two.)

Accepted Answer

Increase the number of shards in the stream to raise write capacity, and configure the Kinesis Producer Library with retries and a higher record max buffering time.. Raising shard count increases write capacity, and the Kinesis Producer Library adds retries and buffering so throttled records are not dropped. Alternatively, On-Demand mode scales capacity automatically, and producer-side exponential backoff handles transient throttling. Both approaches improve throughput and durability without rewriting the producer application.

Answer

Enable server-side encryption on the stream and increase the data retention period to 365 days to prevent event loss.

Answer

Enable enhanced fan-out on the stream so consumers get dedicated throughput, and increase the number of shards to handle higher write throughput.

Answer

Replace the Kinesis data stream with an Amazon SQS standard queue and have producers send messages directly to the queue without retries.

Question 4

A healthcare company runs a patient-records API on an Auto Scaling group of Amazon EC2 instances behind an Application Load Balancer, spanning three Availability Zones. Compliance requires that the application remain writable during the loss of any single Availability Zone, and that no committed write be lost. The team wants to minimize changes to application code. Which solution BEST meets these requirements?

Accepted Answer

Deploy the application across three Availability Zones and store data in an Amazon RDS for MySQL Multi-AZ DB instance deployment with a synchronous standby in a second AZ.. A Multi-AZ DB instance deployment keeps a synchronously replicated standby in a separate AZ, so committed writes survive an AZ failure, and RDS performs automatic failover with an endpoint update. Combined with an Auto Scaling group that spans AZs and an ALB, the application stays writable with minimal code changes, meeting both stated requirements.

Answer

Deploy the application across three Availability Zones and use an Amazon Aurora MySQL DB cluster with a writer instance in one AZ and Aurora Replicas in the other two AZs.

Answer

Deploy the application across three Availability Zones and place an Amazon ElastiCache for Redis cluster in front of the database to absorb writes during an AZ outage.

Answer

Deploy the application across three Availability Zones and use Amazon DynamoDB with a global secondary index, relying on DynamoDB's built-in multi-AZ durability.

Question 5

A logistics company runs an order-processing application on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer. The application stores session state locally on each instance. During scaling events, users are sometimes routed to a different instance and lose their session, forcing them to log in again. The company wants to make the application resilient to instance failures and scaling events without changing the application code. (Choose two.)

Accepted Answer

Store session state in an Amazon ElastiCache for Redis cluster and configure the application to read and write sessions there.. Externalizing session state is the correct way to make a fleet stateless and resilient. ElastiCache for Redis and DynamoDB both provide durable, shared session stores that any instance can access. When an instance fails or a scaling event occurs, the session data persists independently of compute. This eliminates the need for sticky sessions and allows the load balancer to distribute requests freely across healthy instances.

Answer

Configure the Auto Scaling group to use a termination policy that terminates the oldest instance first.

Answer

Enable sticky sessions (session affinity) on the Application Load Balancer so that each user is consistently routed to the same instance.

Answer

Increase the desired capacity of the Auto Scaling group and enable detailed monitoring to reduce the frequency of scaling events.

Question 6

A development team is deploying a stateless containerized application on Amazon ECS using the Fargate launch type. The application must remain available even if a single Availability Zone becomes unavailable. The ECS service should automatically replace unhealthy tasks. What should the team do to meet these requirements with the least effort?

Accepted Answer

Create an ECS service with a desired count of 2 and configure the task placement to spread tasks across multiple Availability Zones.. Spreading ECS tasks across multiple Availability Zones with a desired count of at least two ensures that the application remains available if one AZ fails. The ECS service scheduler automatically replaces unhealthy tasks, and the spread placement strategy distributes tasks for resilience. Other options either confine tasks to one AZ or use inappropriate scheduling strategies, failing the availability requirement.

Answer

Use an Application Load Balancer with a single target group and register tasks from one Availability Zone.

Answer

Configure the ECS service to use the daemon scheduling strategy so that one task runs on every container instance.

Answer

Deploy the ECS service in a single Availability Zone and enable automatic scaling based on CPU utilization.

Question 7

A logistics company runs a stateful application on a single Amazon EC2 instance in one Availability Zone. The application stores session state on an attached Amazon EBS volume. The company wants to make the application resilient to an Availability Zone failure with minimal changes and without rewriting the application to be stateless. Which solution meets these requirements?

Accepted Answer

Move the session state to an Amazon ElastiCache for Redis cluster with Multi-AZ enabled, and run the application on an Auto Scaling group spanning multiple Availability Zones.. To survive an AZ failure with a stateful application, session state must be externalized to a service that replicates across AZs. ElastiCache for Redis with Multi-AZ automatically fails over and preserves session data, while an Auto Scaling group across AZs replaces compute capacity, achieving resilience with minimal application changes.

Answer

Take frequent EBS snapshots and copy them to a second Availability Zone, then restore the volume manually if the primary AZ fails.

Answer

Enable Amazon EBS Multi-Attach on the existing volume and attach it to instances in both Availability Zones.

Answer

Create an Amazon Machine Image (AMI) of the instance and launch a standby instance in a second Availability Zone, then use an Application Load Balancer with health checks to route traffic.

Question 8

A logistics company runs a stateless order-tracking API on a fleet of Amazon EC2 instances behind an Application Load Balancer (ALB). The ALB spans three Availability Zones in a single Region, and the fleet is spread evenly across the same three AZs. The operations team must ensure that a failure of one entire Availability Zone does not interrupt the API, and that health checks remove only unhealthy targets. Which configuration change BEST meets these requirements?

Accepted Answer

Enable cross-zone load balancing on the ALB and keep the target group's health check on the default HTTP path with a 30-second interval.. Distributing targets across multiple Availability Zones and enabling cross-zone load balancing ensures that healthy targets in surviving AZs continue to receive traffic when one AZ fails. A properly configured health check then removes only genuinely unhealthy targets, which is exactly the resilient behavior required.

Answer

Disable cross-zone load balancing on the ALB so each node only routes to targets in its own Availability Zone.

Answer

Keep the ALB but register all targets in a single Availability Zone and rely on the ALB's internal redundancy.

Answer

Replace the ALB with a Network Load Balancer and enable sticky sessions on the target group.

Question 9

A company is designing a disaster recovery strategy for a critical application that runs on AWS. The application uses an Amazon RDS for PostgreSQL database and stores static assets in Amazon S3. The recovery point objective (RPO) is 5 minutes, and the recovery time objective (RTO) is 2 hours. The company wants a cost-effective solution that meets these objectives. Which two actions should be taken? (Choose two.)

Accepted Answer

Enable automated backups for the RDS database with a retention period of at least 1 day, and enable point-in-time recovery.. Enabling RDS automated backups with point-in-time recovery provides a low-cost way to achieve a 5-minute RPO by allowing restore to any point within the retention window. Configuring S3 cross-region replication ensures static assets are available in another region, supporting both RPO and RTO. Together, these actions meet the objectives cost-effectively without running a full standby environment.

Answer

Deploy a warm standby environment in a second region with a scaled-down version of the application fleet.

Answer

Create an Amazon RDS read replica in a second region and promote it during a disaster.

Answer

Use AWS Database Migration Service (DMS) to continuously replicate the RDS database to an Amazon EC2 instance in another region.

Question 10

A healthcare company runs a patient portal on a fleet of Amazon EC2 instances behind an Application Load Balancer. The instances are in an Auto Scaling group that spans three Availability Zones in us-east-1. The company requires the application to remain available even if an entire Availability Zone fails. The instances store no session data locally; sessions are managed in Amazon ElastiCache for Redis. What is the MOST cost-effective way to ensure the application remains available during a single Availability Zone failure?

Accepted Answer

Deploy the Auto Scaling group across three Availability Zones with a desired capacity of three instances and enable ELB health checks.. The application is stateless because sessions are stored in ElastiCache, so any instance can handle any request. Distributing three instances across three AZs ensures that if one AZ fails, the remaining two instances in the other AZs continue to serve traffic. ELB health checks enable automatic replacement of unhealthy instances. This design is cost-effective because it uses the minimum number of instances needed to survive an AZ failure while leveraging the existing multi-AZ Auto Scaling group.

Answer

Replace the Application Load Balancer with a Network Load Balancer and enable cross-zone load balancing.

Answer

Create a second Auto Scaling group in a different AWS Region and use Amazon Route 53 failover routing to direct traffic to the secondary Region.

Answer

Configure the Auto Scaling group to maintain a desired capacity of at least two instances in each of the three Availability Zones.

Question 11

A retail company runs a stateful order-processing application on a single Amazon EC2 instance with an Amazon EBS volume attached. The application writes transaction logs to the instance store and the database files to the EBS volume. The team must redesign the architecture so that the loss of the EC2 instance does not cause data loss or prolonged downtime. (Choose two.)

Accepted Answer

Place the EC2 instance in an Auto Scaling group with a minimum and desired capacity of one, spanning multiple Availability Zones.. Persisting state on EBS with snapshots protects the database files across instance failures, while an Auto Scaling group spanning multiple Availability Zones automatically replaces a failed instance to reduce downtime. Together these two changes remove the single points of failure for both data and compute.

Answer

Enable termination protection on the EC2 instance to prevent the instance from being terminated during a failure.

Answer

Create an Amazon Machine Image of the instance and manually relaunch a new instance from it during an incident.

Answer

Keep the transaction logs on the instance store because instance store volumes are replicated across Availability Zones.

Question 12

A startup hosts a static marketing website on a single Amazon EC2 instance in one Availability Zone, with the web server storing sessions locally. The company needs the site to survive an Availability Zone failure with automatic recovery and no manual intervention. Which approach BEST meets this requirement with the least architectural change?

Accepted Answer

Move the website to an Amazon S3 bucket configured for static website hosting and serve it through Amazon CloudFront.. Because the site is static, hosting it on Amazon S3 eliminates the single EC2 instance and its AZ dependency, since S3 stores data redundantly across Availability Zones. Serving through CloudFront adds performance and further resilience, meeting the automatic-recovery requirement with minimal ongoing operational effort.

Answer

Enable detailed monitoring on the instance and configure an Amazon CloudWatch alarm to reboot the instance when it becomes unhealthy.

Answer

Attach an Elastic Load Balancer to the instance and enable sticky sessions to keep users on the same backend.

Answer

Create an Amazon Machine Image of the instance and configure an Auto Scaling group with a desired capacity of one in the same Availability Zone.

Question 13

A company is designing a disaster recovery (DR) strategy for a critical application that runs on AWS. The application uses an Amazon RDS for PostgreSQL database and stores static assets in Amazon S3. The company has an RPO of 15 minutes and an RTO of 2 hours. The DR site must be in a different AWS Region. The company wants to minimize costs while meeting the RPO and RTO. Which two actions should be taken to meet these requirements? (Choose two.)

Accepted Answer

Enable S3 Cross-Region Replication (CRR) for the bucket that stores static assets.. To meet the RPO of 15 minutes and RTO of 2 hours with minimal cost, the company should use cross-Region read replicas for RDS and S3 Cross-Region Replication. Cross-Region read replicas provide an asynchronous copy of the database that can be promoted quickly, while S3 CRR replicates static assets automatically. Both are managed features that minimize operational overhead and cost.

Answer

Use AWS Database Migration Service (AWS DMS) with change data capture (CDC) to continuously replicate data to an Amazon RDS for PostgreSQL instance in the DR Region.

Answer

Create an Amazon S3 bucket in the DR Region and configure the application to write to both buckets simultaneously.

Answer

Set up a Multi-AZ deployment for the RDS database in the primary Region and use a pilot light approach in the DR Region.

Question 14

A media company stores processed video assets in an Amazon S3 bucket in eu-west-1 and needs a copy in us-east-2 for disaster recovery. The compliance team requires that the copy be created automatically for all new objects and that the source bucket's objects remain unchanged. The team also wants to minimize replication latency and storage cost for objects that are rarely accessed in the destination. Which configuration BEST meets these requirements?

Accepted Answer

Configure S3 Cross-Region Replication with versioning enabled on both buckets, and set the destination storage class to S3 Standard-IA for replicated objects.. Cross-Region Replication automatically copies new objects to a bucket in another Region while leaving the source intact, and it requires versioning on both buckets. Choosing S3 Standard-IA for the destination lowers storage cost for infrequently accessed objects while keeping them immediately available for recovery.

Answer

Configure S3 Cross-Region Replication with versioning enabled on both buckets and set the destination storage class to S3 Glacier Instant Retrieval.

Answer

Enable S3 Versioning on the source bucket only and rely on the version history to serve as the disaster-recovery copy.

Answer

Configure S3 Same-Region Replication within eu-west-1 and use a lifecycle policy to move the copies to us-east-2.

Question 15

An order-processing service consumes messages from an Amazon SQS Standard queue using a custom worker. During traffic spikes, the worker occasionally times out after performing some work but before acknowledging the message, so SQS redelivers it and it may be processed again.

You also observe that a small set of “poison” messages always fail validation.

What change most directly improves resilience by (1) preventing poison messages from retrying indefinitely and (2) avoiding duplicate side effects caused by legitimate retries?

Accepted Answer

Configure a dead-letter queue (DLQ) with a redrive policy that moves messages after maxReceiveCount, and implement idempotent processing in the consumer using an idempotency key.. A dead-letter queue (DLQ) with a maxReceiveCount redrive policy directly addresses the poison message problem by moving messages that repeatedly fail validation out of the main queue after a set number of retries, preventing indefinite retries. Implementing idempotent processing using an idempotency key ensures that even if a legitimate message is redelivered due to a visibility timeout, the consumer can detect and skip duplicate side effects, thus solving both requirements most directly.

Answer

Increase the SQS visibility timeout and, when validation fails, call DeleteMessage in the consumer to remove the message immediately.

Answer

Move to SNS topics with subscriptions and rely on SNS to provide exactly-once delivery to eliminate duplicates automatically.

Answer

Change the queue to FIFO and enable content-based deduplication, leaving the consumer logic unchanged.