SAA-C03 Design Resilient Architectures — 20 Questions

Question 1

An enterprise application runs on Amazon EC2 instances managed by an Auto Scaling group behind an Application Load Balancer. The application experiences unpredictable traffic spikes, and instances occasionally fail health checks due to heavy load during startup. How should the Solutions Architect configure the Auto Scaling group to ensure high availability and prevent premature termination of booting instances?

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

Answer

Implement a lifecycle hook that places launching instances into a pending state, and manually resume instances after checking their log files.

Answer

Set the termination policy to OldestInstance and configure a health check grace period that matches the average application startup time.

Answer

Change the health check type from ELB to EC2, and rely solely on underlying hypervisor status checks to determine instance health.

Answer

Increase the desired capacity of the Auto Scaling group and configure target tracking scaling policies based on CPU utilization metrics.

Question 2

Refer to the exhibit. A Solutions Architect applied an Amazon S3 bucket policy to restrict data access exclusively to a specific VPC endpoint. However, after applying the policy, legitimate applications running inside the authorized VPC endpoint are completely blocked from accessing the bucket. What is the cause of this failure?

Accepted Answer

The policy lacks an explicit Allow statement, and because Deny statements override everything, all requests including those from the correct VPC endpoint are denied.. The issue occurs because the policy uses a 'Deny' effect with 'StringNotEquals' on 'aws:SourceVpce'. This logic denies all requests that do not originate from the specified VPC endpoint. Because S3 bucket policies are evaluated for every request, including those from AWS services or internal management tasks that do not originate from the VPC endpoint, the 'Deny' statement triggers. The correct approach is to use an 'Allow' statement with a 'Condition' block, or a 'Deny' statement with a 'StringNotEquals' condition that also includes a check for the specific IAM roles/users or service principals that need access.

Answer

The `aws:SourceVpce` condition key is only supported on AWS IAM user policies and cannot be evaluated within Amazon S3 resource-based bucket policies.

Answer

Requests originating from within the authorized VPC endpoint also require a matching `aws:SourceVpc` condition key to validate the parent Virtual Private Cloud.

Answer

Certain AWS service actions and management operations do not carry the VPC endpoint context, causing the `StringNotEquals` check to evaluate as true and trigger the Deny rule.

Question 3

A developer is building a serverless application with unpredictable, intermittent traffic patterns. The database must scale capacity automatically to handle bursts and shut down during periods of inactivity to save costs. Which database service is most appropriate?

Accepted Answer

Amazon Aurora Serverless.. Amazon Aurora Serverless is designed for intermittent, unpredictable workloads: it automatically scales compute capacity up and down based on demand and can pause during inactivity, billing only for capacity consumed. This matches the requirement to handle bursts and shut down during idle periods to save costs. DynamoDB with provisioned capacity requires manual capacity planning and does not pause, while RDS Provisioned IOPS and Redshift Spectrum are not serverless auto-scaling databases for transactional workloads.

Answer

Amazon RDS for PostgreSQL with Provisioned IOPS.

Answer

Amazon DynamoDB with Provisioned Capacity.

Answer

Amazon Redshift Spectrum.

Question 4

A solutions architect is designing a VPC for a highly resilient application across three Availability Zones. The application needs outbound internet access for updates but must not be reachable from the internet. Which TWO components are required?

Accepted Answer

NAT Gateways in each of the three Availability Zones.. Option B is correct because a NAT Gateway provides outbound-only internet access for instances in private subnets, and deploying one in each of the three Availability Zones ensures the high resilience requirement is met (a NAT Gateway is AZ-scoped, so one per AZ avoids a cross-AZ single point of failure). Option D is correct because private subnet route tables must contain a route (e.g., 0.0.0.0/0) targeting the NAT Gateway in the same AZ for traffic to actually reach the internet; without this route, the NAT Gateway is unreachable. Option A is not required because an Internet Gateway is only needed for public subnets and would make resources potentially reachable from the internet, which the scenario forbids. Option C is incorrect because an Egress-Only Internet Gateway is used for IPv6 outbound traffic, not the typical IPv4 outbound scenario described. Option E is incorrect because a Customer Gateway is used for Site-to-Site VPN connections to on-premises networks, not for providing internet access.

Answer

An Internet Gateway attached to the VPC.

Answer

An Egress-Only Internet Gateway.

Answer

A Customer Gateway for VPN connectivity.

Question 5

Refer to the exhibit. A solutions architect is reviewing the bucket policy for a sensitive data repository. What is the effect of this policy?

Accepted Answer

It explicitly denies any request that does not use HTTPS.. The bucket policy likely includes a condition that denies requests where 'aws:SecureTransport' is false, which means any request not using HTTPS (i.e., HTTP) is explicitly denied. This is a common security measure to enforce encryption in transit.

Answer

It allows all requests as long as they are encrypted at rest.

Answer

It prevents users from deleting objects unless they use MFA.

Answer

It restricts access to the bucket to only internal AWS services.

Question 6

Refer to the exhibit. The Auto Scaling group is configured with the 'OldestInstance' termination policy. If a scale-in event occurs, which instance will the ASG terminate first?

Accepted Answer

Instance i-111 because it is the oldest in the AZ with the most instances.. The 'OldestInstance' termination policy terminates the instance with the earliest launch time. However, when multiple instances have the same launch time (or when the policy is combined with AZ balancing), AWS first balances the number of instances across Availability Zones. In the exhibit, i-111 is the oldest instance in the AZ that currently has the most instances, so it is selected for termination first. This ensures even distribution across AZs before applying the age-based rule.

Answer

Instance i-333 because it has the earliest launch time overall.

Answer

Instance i-222 because the 'Default' policy is evaluated first.

Answer

The ASG will randomly select an instance to terminate.

Question 7

An application uses an Auto Scaling group with instances across three Availability Zones. The architect wants to ensure the application remains available even if one AZ experiences a total network isolation. What is the most effective way to ensure this?

Accepted Answer

Increase the minimum instance count to cover the capacity of one AZ.. Increasing the minimum instance count to cover the capacity of one AZ ensures that if one AZ is isolated, the remaining instances in the other two AZs can handle the full load. This is the most effective way to maintain availability because it provides sufficient capacity redundancy without relying on the isolated AZ.

Answer

Use a single large instance in each AZ instead of multiple small ones.

Answer

Configure the ALB to ignore unhealthy instances in the isolated AZ.

Answer

Switch to a single-AZ deployment with a standby instance in another region.

Question 8

A company wants to ensure high availability for their application. Which THREE of these services are inherently regional in their high-availability configuration?

Accepted Answer

Amazon S3.. Amazon S3 (A) is inherently regional in its high-availability design because it automatically replicates objects across multiple Availability Zones within a single AWS Region, providing 99.999999999% durability without any cross-region configuration. Amazon RDS (C) achieves high availability regionally through Multi-AZ deployments, which synchronously replicate data to a standby instance in a different Availability Zone within the same Region. Amazon DynamoDB (D) is also inherently regional, as it automatically replicates table data across three Availability Zones within a Region by default, delivering built-in high availability. Amazon EC2 (B) is not inherently regional for HA because an individual instance runs in a single Availability Zone; regional resilience requires the customer to architect across multiple AZs using load balancers and Auto Scaling. Amazon EBS (E) is not inherently regional either, since an EBS volume is tied to a single Availability Zone and only achieves AZ-level redundancy through snapshots or replication that the customer must configure.

Answer

Amazon EC2.

Answer

Amazon EBS.

Question 9

An enterprise financial application runs on a fleet of Amazon EC2 instances behind an Application Load Balancer. The database layer utilizes Amazon RDS for PostgreSQL with Multi-AZ enabled. During routine maintenance or unexpected hardware degradation, connections to the database drop, causing user transactions to fail intermittently. How should the architect redesign the data tier for better fault tolerance?

Accepted Answer

Deploy Amazon RDS Proxy between the EC2 application instances and the RDS PostgreSQL database cluster.. Deploy Amazon RDS Proxy between the EC2 application instances and the RDS PostgreSQL database cluster. RDS Proxy pools and shares database connections, improving scalability and making applications more resilient to database failures by handling connection drops and failovers transparently.

Answer

Migrate the PostgreSQL database to an Amazon DynamoDB global table with strongly consistent reads.

Answer

Configure Amazon Route 53 DNS failover with a very short TTL pointing directly to the RDS read replica endpoint.

Question 10

A company hosts a web application on EC2 instances behind an Application Load Balancer (ALB). The application requires high availability across two Availability Zones. Which configuration ensures the most resilient traffic distribution?

Accepted Answer

Enable Cross-Zone Load Balancing on the Application Load Balancer.. Enabling Cross-Zone Load Balancing on an Application Load Balancer allows the ALB nodes in each Availability Zone to distribute traffic evenly across all registered targets in all enabled AZs, ensuring that if one AZ has fewer healthy targets, traffic is still balanced across the remaining healthy targets in other AZs. This provides the most resilient traffic distribution across two AZs.

Answer

Place instances in a single Auto Scaling group with a minimum size of zero.

Answer

Use a Network Load Balancer with static IP addresses in each zone.

Answer

Configure Route 53 with a latency-based routing policy to the ALB.

Question 11

Refer to the exhibit. An application running on EC2 needs to store backups in an S3 bucket. The administrator applied the policy in the exhibit, but the EC2 instance cannot upload objects. What is the most likely cause?

Accepted Answer

The resource ARN must include the bucket name without the wildcards.. The s3:PutObject action is an object-level permission that requires the resource ARN to include a wildcard suffix (e.g., arn:aws:s3:::bucket-name/*) to specify the objects within the bucket. If the ARN only specifies the bucket itself (arn:aws:s3:::bucket-name), the put operation will be denied.

Answer

The policy is missing the s3:ListBucket permission.

Answer

The policy is missing a Deny statement to prevent unauthorized access.

Answer

The action s3:PutObject is not supported for S3 buckets.

Question 12

A company wants to ensure that its Amazon EBS volumes are protected against data loss due to an Availability Zone failure. What is the most effective solution?

Accepted Answer

Regularly create EBS snapshots and copy them to another region.. Amazon EBS volumes are tied to a specific Availability Zone. To protect data against an Availability Zone failure, you can create EBS snapshots. EBS snapshots are incrementally backed up to Amazon S3, which is designed for 9-nines of durability and automatically replicates data across multiple Availability Zones within a region. Therefore, taking regular snapshots ensures data can be restored in a different AZ within the same region.

Answer

Enable RAID 0 across multiple EBS volumes.

Answer

Use Amazon EFS instead of EBS for all applications.

Answer

Attach a single EBS volume to multiple EC2 instances.

Question 13

An application relies on a message queue to decouple services. The architect wants to ensure that messages are not lost if the queue service is temporarily unavailable. What should be done?

Accepted Answer

Use Amazon SQS with default settings.. The explanation correctly identifies SQS as the solution, but the trap notes discuss EC2 Placement Groups, which have nothing to do with message queuing or SQS.

Answer

Implement a local database to store messages before queuing.

Answer

Use an in-memory Redis cluster for message storage.

Answer

Only process messages during off-peak hours.

Question 14

An architect is designing a web application and wants to ensure that static assets are delivered with low latency and high availability. Which THREE actions are recommended? (Select THREE.)

Accepted Answer

Use Amazon CloudFront for content distribution.. Option A is correct because Amazon CloudFront is AWS's global CDN, caching static assets at edge locations worldwide to reduce latency and improve availability for end users. Option B is correct because Amazon S3 provides highly durable, scalable, and highly available object storage designed for serving static assets such as images, CSS, and JavaScript. Together, S3 as the origin plus CloudFront as the distribution is the standard AWS pattern for low-latency, highly available static content delivery. Option C is not correct because S3 Transfer Acceleration speeds up uploads to a bucket, not downloads of static assets to end users. Option D is not correct because hosting static files on the same EC2 instance as the application couples availability and scaling, and provides no global edge caching. Option E is not correct because RDS is a relational database, not an appropriate or cost-effective store for serving static image files.

Answer

Enable S3 Transfer Acceleration on the bucket.

Answer

Host static files on the same EC2 instance as the application.

Answer

Use an RDS database to store all static image files.

Question 15

Refer to the exhibit. An application uses an Amazon S3 bucket to store critical backup files. The architect needs to ensure that these backups are protected from accidental deletion and that the bucket itself is highly available. Which configuration should the architect implement?

Accepted Answer

Enable S3 Versioning and MFA Delete on the bucket.. S3 Versioning preserves every version of an object so an accidental overwrite or delete can be recovered, and MFA Delete adds a second authentication factor requirement for permanently deleting object versions or changing the bucket's versioning state. Together they directly address the requirement to protect backups from accidental deletion while S3's built-in multi-AZ design provides high availability.

Answer

Configure the bucket for S3 Cross-Region Replication.

Answer

Use S3 Object Lock in compliance mode for all objects.

Answer

Apply a bucket policy that denies s3:DeleteObject to all IAM users.

Question 16

A financial services company is hosting a critical web application on Amazon EC2 instances behind an Application Load Balancer. The application must remain available even if an entire AWS Region experiences a major outage. The database tier uses Amazon Aurora Global Databases. Which solution provides the most resilient multi-Region architecture with automated failover?

Accepted Answer

Deploy the application stack across two AWS Regions, use Amazon Route 53 with active-passive failover and automated health checks, and configure Amazon Aurora Global Databases with cross-region replication.. Deploying Route 53 with active-passive failover and automated health checks combined with a secondary Region ensures automatic traffic rerouting during a regional disaster. Aurora Global Databases minimize replication lag and permit fast promotion of the secondary region database, maintaining data consistency and business continuity for critical financial applications requiring minimal recovery time objectives.

Answer

Configure an Application Load Balancer in a single Region with EC2 instances distributed across multiple Availability Zones, and back the application with a standard Aurora MySQL database instance.

Answer

Use Amazon Route 53 with weighted routing policies to distribute traffic between two AWS Regions, and configure standard cross-region database replication using Amazon RDS snapshots taken every hour.

Answer

Set up an AWS Global Accelerator standard accelerator with endpoint groups in two AWS Regions, and use Amazon DynamoDB global tables with local secondary indexes for data storage.

Question 17

A media streaming company stores high-value video assets in an Amazon S3 bucket. The company requires a resilient storage architecture that protects against accidental deletion, malicious overwrites, and zonal or regional outages. Which combinations of features should a Solutions Architect implement to achieve these requirements? (Choose TWO.)

Accepted Answer

Enable S3 Versioning on the bucket and configure MFA Delete to prevent accidental or malicious deletion of object versions.. Enabling S3 Versioning ensures that previous versions are retained when objects are deleted or overwritten, protecting against accidental data loss. Furthermore, replicating objects to another AWS Region using S3 Cross-Region Replication guarantees durability and availability against catastrophic regional disruptions, satisfying robust disaster recovery best practices for critical media assets.

Answer

Configure Amazon S3 Intelligent-Tiering to automatically move infrequently accessed video assets to lower-cost storage tiers.

Answer

Attach a resource-based bucket policy that explicitly denies all delete object requests from any IAM user except the root account.

Answer

Enable S3 Object Lock in governance mode with a fixed retention period of 30 days for all uploaded video files.

Question 18

A company hosts a web application on EC2 instances behind an Application Load Balancer. The application stores session state in local memory, causing users to be logged out whenever the load balancer routes requests to different instances. Which solution provides the most resilient, scalable architecture to resolve this?

Accepted Answer

Store session state in Amazon ElastiCache for Redis.. Storing session state in Amazon ElastiCache for Redis externalizes session data so any EC2 instance behind the ALB can serve any request, eliminating the logout problem while providing high availability and scalability. Redis is purpose-built for low-latency session stores and supports replication and failover. This is the AWS-recommended pattern for stateless web tiers.

Answer

Configure the Application Load Balancer to use source IP stickiness.

Answer

Use Amazon EBS multi-attach to share session files across instances.

Answer

Replicate session files using a cron job across all web instances.

Question 19

A company's web application requires a highly available database layer to survive an Availability Zone failure without manual intervention. The database must remain accessible during maintenance windows and ensure zero data loss. Which solution meets these requirements with the least operational overhead?

Accepted Answer

Implement an Amazon RDS Multi-AZ deployment.. Amazon RDS Multi-AZ maintains a synchronous standby replica in a different Availability Zone and automatically fails over during an AZ failure or maintenance event, with zero data loss (RPO=0) and no manual intervention. It meets high availability, maintenance resilience, and zero data loss with minimal operational overhead.

Answer

Configure RDS Read Replicas and manually promote them during an outage.

Answer

Deploy a Single-AZ RDS instance and use AWS Backup for hourly snapshots.

Answer

Host a MySQL database on an Amazon EC2 instance with an EBS volume.

Question 20

An application is deployed across two AWS Regions to ensure resilience. The architect needs to direct users to the healthy region with the lowest latency. If the primary region fails, traffic should fail over automatically. Which Route 53 routing policy should be implemented?

Accepted Answer

Latency routing policy with health checks.. Latency-based routing with health checks directs each user to the AWS Region that provides the lowest latency while the health check removes an unhealthy region's records from DNS responses, achieving automatic failover. This satisfies both requirements: lowest-latency selection under normal conditions and automatic redirection when the primary region fails.

Answer

Simple routing policy.

Answer

Failover routing policy.

Answer

Weighted routing policy.