AWS Certified Solutions Architect – Professional — Question 66

To serve Web traffic for a popular product your chief financial officer and IT director have purchased 10 m1.large heavy utilization Reserved Instances (RIs), evenly spread across two availability zones; Route 53 is used to deliver the traffic to an Elastic Load Balancer (ELB). After several months, the product grows even more popular and you need additional capacity. As a result, your company purchases two C3.2xlarge medium utilization Ris. You register the two c3.2xlarge instances with your ELB and quickly find that the m1.large instances are at 100% of capacity and the c3.2xlarge instances have significant capacity that's unused.
Which option is the most cost effective and uses EC2 capacity most effectively?

Answer options

• A. Configure Autoscaling group and Launch Configuration with ELB to add up to 10 more on-demand m1.large instances when triggered by Cloudwatch. Shut off c3.2xlarge instances.
• B. Configure ELB with two c3.2xlarge instances and use on-demand Autoscaling group for up to two additional c3.2xlarge instances. Shut off m1.large instances.
• C. Route traffic to EC2 m1.large and c3.2xlarge instances directly using Route 53 latency based routing and health checks. Shut off ELB.
• D. Use a separate ELB for each instance type and distribute load to ELBs with Route 53 weighted round robin.

Correct answer: D

Explanation

Using a separate ELB for each instance type allows for better traffic management and ensures that the m1.large and c3.2xlarge instances are utilized according to their capacities. Option A and B do not effectively address the issue of capacity distribution between instance types, while option C eliminates the benefits of using ELB which provides load balancing. Therefore, option D is the most cost-effective and capacity-efficient solution.