Answer: Use a target tracking scaling policy to scale the Auto Scaling group based on instance CPU utilization., Use scheduled scaling to change the Auto Scaling group minimum, maximum, and desired capacity to zero for weekends. Revert to the default values at the start of the week.

## Explanation **Correct Answers: D and E** **D. Use a target tracking scaling policy to scale the Auto Scaling group based on instance CPU utilization.** - Target tracking scaling policies automatically adjust the number of EC2 instances in an Auto Scaling group to maintain a specific target metric value (like average CPU utilization). - This is ideal for handling unpredictable traffic spikes during working hours, as it dynamically scales based on actual resource utilization. - When CPU utilization increases due to higher traffic, the policy will automatically add more instances to handle the load. **E. Use scheduled scaling to change the Auto Scaling group minimum, maximum, and desired capacity to zero for weekends. Revert to the default values at the start of the week.** - Since the system is "not required to operate on weekends," scheduled scaling is perfect for this requirement. - Scheduled scaling allows you to set specific times to change the Auto Scaling group's capacity. - Setting capacity to zero on weekends eliminates unnecessary costs when the system is not needed. - Reverting to normal values at the start of the week ensures the system is ready for Monday's traffic. **Why the other options are incorrect:** **A. Use AWS Auto Scaling to adjust the ALB capacity based on request rate.** - ALBs don't have "capacity" that needs scaling in this context. ALBs automatically scale to handle traffic, and you don't manually adjust their capacity. - The scaling should focus on the EC2 instances behind the ALB, not the ALB itself. **B. Use AWS Auto Scaling to scale the capacity of the VPC internet gateway.** - Internet gateways are highly available, horizontally scaled AWS-managed components that automatically handle traffic. - You cannot scale internet gateway capacity using Auto Scaling - they are not Auto Scaling resources. **C. Launch the EC2 instances in multiple AWS Regions to distribute the load across Regions.** - While multi-region deployment improves resilience and can handle global traffic, it's overkill for a "software demonstration environment" with predictable weekly patterns. - Multi-region deployment adds significant complexity and cost without being necessary for the stated requirements. - The requirement mentions traffic increases during working hours, not global distribution needs. **Key AWS Concepts:** 1. **Target Tracking Scaling Policies**: Best for dynamic scaling based on metrics like CPU utilization, request count per target, or average network in/out. 2. **Scheduled Scaling**: Ideal for predictable load patterns (like daily/weekly cycles). 3. **Cost Optimization**: Setting capacity to zero when not needed is a fundamental cost optimization strategy in AWS. 4. **ALB Auto Scaling**: ALBs automatically scale to handle traffic; you only need to scale the targets (EC2 instances) behind them.