SAA-C03 Q618 · Scaling

Question

A company deployed a three-tier web application in a single Availability Zone in the us-east-1 Region on a single Amazon EC2 instance. Usage of the application is growing. A solutions architect needs to ensure that the application can handle the growing amount of traffic and that the application is resilient. The solution must be cost-effective. Which solution will meet these requirements MOST cost-effectively?

Accepted Answer

**Answer D** satisfies every requirement:

1. **Handle growing traffic**: An EC2 Auto Scaling group with **dynamic scaling based on CloudWatch alarms** automatically adds or removes instances as traffic fluctuates. This is horizontal scaling — adding more instances rather than making one bigger.

2. **Resilience**: Instances are **spread across multiple Availability Zones**. If one AZ goes down, the ALB routes traffic to healthy instances in the remaining AZs. The Auto Scaling group will also automatically launch replacement instances in healthy AZs.

3. **Cost-effective**: Auto Scaling means you only pay for the capacity you need. A minimum of 3 instances (e.g., 1 per AZ across 3 AZs) provides a baseline for resilience without over-provisioning. Dynamic scaling via CloudWatch alarms ensur

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📘 Key Concepts

🏗️ Architecture

⚙️ Operations

💰 Cost

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