The medical reports needreal-time accesseven though they are read only about once a year, which matchesS3 Glacier Instant Retrieval. AWS documents that objects in Glacier Instant Retrieval are immediately available with GET, making it the right archival class when access is infrequent but still must be immediate. The medical images are rarely accessed and can tolerate slower retrieval, soS3 Glacier Deep Archiveis the lowest-cost long-term archival choice. AWS recommends Deep Archive for long-lived data that is accessed less than once a year and can wait hours to days for restore completion. That combination optimizes cost while still meeting the very different retrieval requirements for reports and images. (AWS Documentation)

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The most effective and AWS-recommended way to mitigate unwanted traffic at the edge is to use AWS WAF integrated with CloudFront. Option D allows the architect to block or throttle malicious traffic before it reaches the ALB or EC2 instances.

Rate-based rules automatically block IP addresses that exceed a defined request threshold, making them ideal for mitigating abusive traffic patterns. This reduces load on backend resources and improves performance for legitimate users.

Options A, B, and C are less effective or introduce unnecessary cost and complexity. Shield does not provide granular rate control, Auto Scaling increases cost, and NACLs are difficult to manage dynamically.

Therefore, D is the correct and most secure solution.

Using Amazon CloudFront in front of an ALB in a single region is a cost-effective way to deliver content with low latency across the globe. CloudFront caches content closer to the users, reducing the load on backend servers and minimizing data transfer costs by serving cached content from edge locations.

Compared to Global Accelerator, CloudFront is significantly more cost-optimized for static and dynamic content delivery. Multi-region deployments increase infrastructure and transfer costs, which violates the optimization goal. Therefore, option A provides the best mix of performance and cost efficiency.

Amazon EC2 Auto Scaling publishes group-level metrics, including the number of in-service instances. A CloudWatch alarm can evaluate whether that count remains above 180 for a continuous 60-minute period. A step scaling action can then reduce desired capacity, allowing the group to support short-lived surges up to 300 instances while limiting the cost of sustained excess capacity. Scheduled scaling cannot handle unpredictable surges, and maximum instance lifetime replaces individual instances rather than controlling total group capacity. Directly terminating instances through an alarm would bypass normal Auto Scaling capacity management. The original option’s wording is technically imperfect because step scaling adjusts desired capacity; it does not directly rewrite the group’s maximum-size property. Option D is correct when interpreted as a scale-in action that reduces desired capacity to approximately 180 instances.

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AWS App2Container is a command-line tool that helps containerize existing Java and .NET applications running on-premises or on virtual machines, with minimal refactoring. By using Amazon EKS, the company benefits from a managed Kubernetes service, which significantly reduces the operational overhead compared to managing Kubernetes on EC2.

Amazon RDS for SQL Server provides a fully managed SQL Server database engine with automated backups, patching, and high availability through Multi-AZ deployments. This eliminates the need for the company to manage database infrastructure and software manually.

Overall, option A provides the most streamlined and managed approach for both the application and database layers with the least operational effort.

IAM user creation and deletion are AWS API management events. CloudTrail records management events such as IAM CreateUser and DeleteUser API calls. EventBridge can match these CloudTrail events with an event pattern and route the matching events to an Amazon SNS topic. Subscribing the company’s email address to the SNS topic provides the required email notification. Amazon Inspector is for vulnerability and exposure findings, not IAM account-change monitoring. GuardDuty can detect suspicious IAM behavior, but it is not the correct service for deterministic notifications every time a user is created or deleted. Amazon Macie is focused on sensitive data discovery and data security findings in services such as Amazon S3, not IAM lifecycle events.

The application is described as stateful, which means user sessions or state are likely stored in memory on the application server. When migrating to an Auto Scaling group behind a load balancer, a consistent user experience typically requires session stickiness, so a user’s subsequent requests continue to be routed to the same backend instance that holds their session state (unless the application is refactored to externalize session state, which is not stated here). For HTTP/HTTPS web applications, an Application Load Balancer (ALB) is the correct Elastic Load Balancing choice because it operates at Layer 7 and provides built-in support for cookie-based sticky sessions.

On the database side, Aurora PostgreSQL supports scaling read capacity by adding Aurora Replicas, and Aurora Auto Scaling can automatically adjust the number of replicas based on demand. This is the intended mechanism to scale the database tier for growing read traffic while preserving write consistency through a single writer. “Aurora writers” do not scale horizontally the same way; Aurora provides one writer endpoint at a time (with fast failover), so auto-scaling “writers” is not the right construct for demand-based scaling.

Option C combines the correct load balancer type (ALB) with stickiness and the correct database scaling mechanism (Aurora Replicas with auto scaling). Option A uses an NLB, which is Layer 4 and does not provide the same Layer 7 sticky session behavior expected for a web application pattern. Options B and D incorrectly focus on scaling Aurora writers, which does not address scaling demand patterns as effectively as scaling read replicas.

Therefore, C provides the most consistent user experience for a stateful web tier and enables the database tier to scale using Aurora Replica auto scaling.

Comprehensive and Detailed Step-by-Step Explanation:

To accurately charge customers based on their monthly data download usage, the following solution is recommended:

Structured Logging Configuration:

Action:Ensure that the AWS Transfer for SFTP server is configured to log user activity, including details about file downloads, to Amazon S3 in a structured format.

Implementation:Utilize AWS Transfer Family ' s structured logging feature to capture detailed information about user sessions, including actions performed and data transferred.

docs.aws.amazon.com

Justification:Structured logs provide comprehensive data necessary for analyzing customer-specific download activities.

Data Analysis with Amazon Athena:

Action:Use Amazon Athena to run SQL queries on the structured log data stored in the S3 bucket to calculate the amount of data each customer has downloaded.

Implementation:

a.Define a Schema:Create a table in Athena that maps to the structure of your log files. This involves specifying the format of the logs and the location in S3.

b.Query Data:Write SQL queries to sum the total bytes downloaded by each customer over the billing period. This can be achieved by filtering logs based on user identifiers and summing the data transfer amounts.

Justification:Athena allows for efficient querying

To improve scalability and availability, EC2 Auto Scaling across multiple Availability Zones with an Application Load Balancer ensures resilient infrastructure. Migrating to Amazon Aurora MySQL with reader endpoints reduces read latency by offloading read traffic to replicas in otherAZs, while also increasing high availability.

For short, frequent daily spikes (15–20 minutes), the most cost-effective scaling behavior typically comes from target tracking scaling driven by a request-based metric, because it continuously adjusts capacity to maintain a chosen target value rather than adding/removing capacity in coarse steps. Option D uses a custom CloudWatch metric representing the number of GET requests (sourced from ALB access logs, application instrumentation, or request counting logic) and applies target tracking so the Auto Scaling group scales out and in proportionally to demand. This helps avoid both under-provisioning (bad performance during spikes) and over-provisioning (wasted cost between spikes), which is exactly what cost-optimized elasticity aims for.

Option A (simple scaling) is usually less cost-efficient for bursty traffic because it relies on fixed adjustments and alarm thresholds, often with cooldowns. With 15–20 minute spikes, simple scaling can react too slowly, overshoot, or oscillate, leaving extra instances running after the spike or failing to ramp fast enough at the start. Option B (predictive scaling) is intended for regular, forecastable demand patterns, but it’s not always the most cost-effective choice for repeated short spikes because it can pre-scale conservatively and may require more historical data and tuning; it is often paired with dynamic scaling anyway. Option C uses UnhealthyHostCount, which is a health signal—not a demand signal—and scaling on unhealthy hosts can increase cost without addressing request volume; it may also mask underlying application issues rather than scaling to meet load.

Because the requirement explicitly allows standard or custom metrics and focuses on scaling based on request volume, D best matches a cost-efficient, responsive approach that directly tracks incoming workload.

For improving availability and performance of the hybrid application, the following solutions are optimal:

AWS Global Accelerator (Option A): Global Accelerator provides high availability and improves performance by using the AWS global network to route user traffic to the nearest healthy endpoint (across AWS Regions). By adding the Network Load Balancers as endpoints, Global Accelerator ensures that traffic is routed efficiently to the closest endpoint, improving both availability and performance.

Network Load Balancer (Option D): Thestateful TCP-based workloadhosted on Amazon EC2 instances and thestateless UDP-based workloadhosted on-premises are best served by Network Load Balancers (NLBs). NLBs are designed to handle TCP and UDP traffic with ultra-low latency and can route traffic to both EC2 and on-premises endpoints.

Option B (CloudFront and Route 53): CloudFront is better suited for HTTP/HTTPS workloads, not for TCP/UDP-based applications.

Option C (ALB): Application Load Balancers do not support the stateless UDP-based workload, making NLBs the better choice for both TCP and UDP.

AWS References:

AWS Global Accelerator

Network Load Balancer

Amazon Route 53 Resolver endpoints allow you to integrate DNS between AWS and on-premises environments easily. By creating inbound and outbound resolver endpoints, you can configure conditional forwarding rules so that DNS queries for your on-premises AD domain are forwarded to the on-premises DNS servers. This approach is fully managed, scales automatically, and requires the least administrative overhead.

AWS Documentation Extract:

" Route 53 Resolver provides DNS resolution between AWS and on-premises environments, using endpoints and forwarding rules to manage DNS query routing seamlessly. "

(Source: Route 53 Resolver documentation)

A, D: Require provisioning, managing, and patching EC2 servers or domain controllers.

B: NS records in a private hosted zone do not provide true DNS forwarding.

The correct answer isCbecause the existing application usesNFS storagefor an image cache that isa few terabytes in size, and the company wants themost cost-effective cloud alternative.Amazon EFS One Zoneis a managed file storage service that supports theNFS protocol, which allows the application to continue using a familiar file-based interface with minimal architectural change. Because this is acache, not primary durable data, storing it in aOne Zonefile system is a cost-optimized choice compared with a Regional EFS deployment.

Amazon EFS is designed for shared file storage and can scale to multiple terabytes automatically. It avoids the operational overhead of managing EC2 instances and local disks for cache storage. It is also better aligned than object storage for workloads that already expect direct NFS semantics. The application can mount the EFS file system and use it as the cache backend without redesigning around object APIs or in-memory caching models.

Option A is incorrect becauseElastiCache Memcachedis an in-memory cache and is typically much more expensive for multi-terabyte cache data than file storage. Option B is incorrect because using EC2 instance store volumes creates significant management overhead and the cache would be lost whenever instances are terminated or replaced. Option D is incorrect becauseAmazon S3 Express One Zoneis object storage, not NFS storage, and would require application redesign and additional metadata management in DynamoDB.

AWS storage guidance recommends matching file-based workloads to managed file services. For a largeNFS-based cache,Amazon EFS One Zoneis the most cost-effective and operationally simple solution.

The requirement is to route users to the nearest AWS Region where the application is deployed. The best solution is to use Amazon Route 53 with a geolocation routing policy, which routes traffic based on the geographic location of the user making the request.

Geolocation Routing: This routing policy ensures that users are directed to the resources (in this case, EC2 instances) that are geographically closest to them, thereby reducing latency and improving the user experience.

Application Load Balancer (ALB): Within each Region, an internet-facing Application Load Balancer (ALB) is used to distribute incoming traffic across multiple EC2 instances in different Availability Zones. ALBs are designed to handle HTTP/HTTPS traffic and provide advanced features like content-based routing, SSL termination, and user authentication.

Why Not Other Options?:

Option B (Geoproximity + NLB): Geoproximity routing is similar but more complex as it requires fine-tuning the proximity settings. A Network Load Balancer (NLB) is better suited for TCP/UDP traffic rather than HTTP/HTTPS.

Option C (Multivalue Answer Routing + ALB): Multivalue answer routing does not direct traffic based on user location but rather returns multiple values and lets the client choose. This does not meet the requirement for geographically routing users.

Option D (Weighted Routing + NLB): Weighted routing splits traffic based on predefined weights and does not consider the user ' s geographic location. NLB is not ideal for this scenario due to its focus on lower-level protocols.

AWS References:

Amazon Route 53 Routing Policies- Detailed explanation of the various routing policies available in Route 53, including geolocation.

Elastic Load Balancing- Information on the different types of load balancers in AWS and when to use them.

This solution meets the requirement of encrypting each customer’s data separately with the least operational overhead by leveraging AWS Key Management Service (KMS).

Separate AWS KMS Keys: By creating separate KMS keys for each customer, you can ensure that each customer’s data is encrypted with a unique key. This approach satisfies the compliance requirement for separate encryption and provides fine-grained control over access to the keys.

Granular Access Control: AWS KMS allows you to define key policies and use IAM policies to grant specific permissions to the keys. This ensures that only authorized users or services can access the keys, thereby maintaining the principle of least privilege.

Logging and Monitoring: AWS KMS integrates with AWS CloudTrail, which logs all key usage and management activities. This provides an audit trail that is essential for meeting compliance requirements.

Why Not Other Options?:

Option A (Store keys in S3): Storing keys in S3 is not recommended because it does not provide the same level of security, access control, or integration with AWS services as KMS does.

Option B (Hardware security appliance): Deploying a hardware security appliance adds significant operational overhead and complexity, which is unnecessary given that KMS already provides a secure and centralized key management solution.

Option C (Single KMS key for all data): Using a single KMS key does not meet the requirement of encrypting each customer ' s data separately.

AWS References:

AWS Key Management Service (KMS)- Overview of KMS, its features, and best practices for key management.

Using AWS KMS for Multi-Tenant Applications- Guidance on how to design applications using KMS for multi-tenancy.