AWS Migration: Highly Available Scalable Web App with SQL Database
Short answer
C Migrate the web application to Amazon EC2 instances that run in an Auto Scaling group across two Availability Zones behind an Application Load Balancer. Migrate the database to Amazon RDS with Multi-AZ deployment.
Question
Key Takeaways
The core trap is confusing standard redundancy with true scalability; only options combining Auto Scaling for compute and Multi-AZ for database provide both HA and elasticity without manual intervention.
This question addresses designing a highly available and scalable architecture for an ecommerce workload on AWS, emphasizing the use of Auto Scaling Groups and RDS Multi-AZ to meet requirements with minimal administrative overhead.
Common mistake: Many learners select Option A because it mentions Read Replicas, which are good for scaling reads, but they fail to recognize that Read Replicas do not provide automatic high availability for writes or handle application-level scaling like an Auto Scaling Group does.
Expert Analysis
Why the Answer Is Correct
Option C is the correct solution because it leverages managed services (Amazon RDS) and elastic compute (Auto Scaling Groups) to achieve both high availability and scalability with the least administrative overhead. The web application uses an Auto Scaling Group across two Availability Zones behind an Application Load Balancer, ensuring that traffic spikes during promotional events are handled automatically by adding or removing instances. Simultaneously, Amazon RDS for Microsoft SQL Server with Multi-AZ deployment provides automatic failover and high availability for the database layer, eliminating the need for manual replication management.
Why the Other Options Are Wrong
Option A fails to provide true scalability for the web tier as it relies on fixed EC2 instances rather than an Auto Scaling Group, meaning it cannot dynamically adjust to the "high volume" mentioned in the scenario. Option B involves cross-region replication for the database, which introduces significant complexity, latency, and administrative overhead, violating the "least administrative overhead" requirement. Option D suggests running three EC2 instances for the database, which requires manual configuration of clustering or replication software, resulting in significantly higher operational burden compared to the managed RDS service.
Community Comment Notes
Community consensus strongly favors Option C, with users noting that "Auto-Scale in 2 AZ for EC2, Database in Multi-AZ" is the standard pattern for this type of workload. One user highlighted that while Option A might seem tempting due to read replicas, it lacks the auto-scaling capability necessary for the described high-volume event. Another commenter pointed out that Option C is the only valid option that satisfies both HA and scalability constraints simultaneously.
Exam Strategy
When asked for 'least administrative overhead,' always prioritize managed services (like RDS over EC2 databases) and automated features (like Auto Scaling over fixed instance counts). Look for keywords like 'scalable' combined with 'highly available' to identify solutions that include both horizontal scaling and multi-AZ redundancy.
Frequently Asked Questions
Why is Option A incorrect if it includes Read Replicas?
Does RDS Multi-AZ improve performance?
Community Votes
100% of anonymous learners picked answer C. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 5 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 5
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Scheldon 👍 3 Answered CAnswerC I would de-couple as many elements as possible with appopriate redundancy (HA), hence Auto-Scale in 2 AZ for EC2, Database in Multi-AZ and ALB infront of EC2. It will allow to increase amount of servers in case of need and will prevent from service unavailability in case if something fail ;)
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zinabu 👍 3 Answered Cyes ''C'' but it was better if it says Amazon RDS for Microsoft SQL Multi-AZ. any ways
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LeonSauveterre 👍 1 Answered CInitially I chose A but then again, "highly available and scalable" should indicate multi az and auto scaling group, so C is the only valid option.
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rondelldell 👍 3 Answered Conly c
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Awsbeginner87 👍 2 Answered AOption a
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