Answer: Create a managed node group that contains only Spot Instances.

## Explanation **Correct Answer: A** - Create a managed node group that contains only Spot Instances. **Why this is the most cost-effective solution:** 1. **Development cluster requirements**: The company needs a dedicated EKS cluster for development work that will be used infrequently to test application resiliency. 2. **Cost optimization with Spot Instances**: Spot Instances are ideal for development/test workloads because: - They offer up to 90% discount compared to On-Demand Instances - They are perfect for fault-tolerant, stateless, and interruptible workloads - Development/testing environments can tolerate interruptions - The infrequent usage pattern aligns perfectly with Spot Instance characteristics 3. **Managed node group requirement**: The question states "The EKS cluster must manage all the nodes." Managed node groups with Spot Instances satisfy this requirement while providing cost savings. **Why other options are not optimal:** - **Option B**: Creating two managed node groups (one On-Demand, one Spot) adds unnecessary complexity and cost. For a development cluster used infrequently, having On-Demand Instances defeats the purpose of cost optimization. - **Option C**: Creating an Auto Scaling group with launch configuration and user data to add nodes to EKS violates the requirement that "The EKS cluster must manage all the nodes." This approach uses self-managed nodes instead of managed node groups. - **Option D**: Creating a managed node group with only On-Demand Instances is the most expensive option and doesn't leverage cost optimization opportunities for a development environment. **Key AWS Concepts:** - **Spot Instances**: Best for workloads that are fault-tolerant, flexible in when they run, and can handle interruptions - **Managed Node Groups**: Automatically manage the lifecycle of nodes (EC2 instances) in an EKS cluster - **Cost Optimization**: Development/test environments should use Spot Instances or Savings Plans to reduce costs **Best Practice**: For development/test EKS clusters, use managed node groups with Spot Instances to achieve the best balance of cost-effectiveness and management simplicity.

Author: LeetQuiz Editorial Team