A client who has adopted AWS cloud services would like to ensure that his systems always scale with increasing traffic for a great end-user experience. I have implemented the same by defining AutoScaling Scale-In & Scale-Out policies & CloudWatch alarms that trigger the AutoScaling. Which Cloud Architecture Design principles have I implemented here? Select TWO most suitable options.

Answer options:

A.Encryption
B.Operational Excellence
C.Performance Efficiency
D.Cost Optimization
E.Least privilege

Answers: B and C
Looking at the scenario, a good end-user experience is attached to systems being performant with increasing load on them. A combination of Load balancing & AutoScaling enables a system to handle increase in load by spinning new instances to which the load will be distributed not to saturate resources like CPU & Memory on a single server instance. For the AutoScaling itself to work efficiently, there needs to be a good monitoring system that can track resource utilization and enable automation. The scenario combines the Operational Excellence & the Performance Efficiency Architecture design principles.
Option A is incorrect. This scenario does not describe anything about data encryptions so that this option is not selected.
Option B is CORRECT. The monitoring mechanism used here is CloudWatch for enabling AutoScaling to happen by tracking resource utilization metrics like CPU and Memory usage. The Operational Excellence pillar focuses on Monitoring systems that will deliver continuous business value by providing automation, responding to events within the system. In our scenario, automating the system`s Scalability through monitoring will help maintain the desired performance levels.
Option C is CORRECT. The Performance Efficiency pillar focuses on monitoring the performance of a system. CloudWatch metrics help monitor a system`s performance by using metrics like CPU, Memory, Disk utilization etc... Automating tasks like AutoScaling using CloudWatch Alarms and defining scaling policies will ensure that the client`s performance requirements will always be met with when there is an increase in traffic.
Option D is incorrect. In spite of using Scale-in & Scale-out policies, I can be benefitted from cutting down idle resource utilization costs. The scenario deals more with Performance & Operational aspects.
Option E is incorrect. Least privilege is a security principle which is not mentioned in the question.
Diagrams:
References:
https://aws.amazon.com/blogs/apn/the-5-pillars-of-the-aws-well-architected-framework/