Q59 — AWS SAA-C03 Ch.17

Question 59 of 89 | ← Chapter 17

Q1359. A company runs Amazon EC2 instances as web servers. Peak traffic load occurs on the web server at two times each day. The web servers are idle for the remainder of the day. A solutions architect needs to manage the web servers and maintain fault tolerance. Which solution will meet these requirements in the MOST cost-effective way?

Correct Answer: A. Use an EC2 Auto Scaling group to scale the instances based on demand.

Explanation

The correct answer is A. Use an EC2 Auto Scaling group to scale the instances based on demand.Explanation:The company needs a cost-effective, fault-tolerant solution for managing EC2 web servers that experience predictable peak traffic twice daily and remain idle otherwise.Key Requirements:Cost-effective Avoid overpaying for unused capacity.Fault-tolerant Ensure high availability during peak traffic. Scalable Handle traffic spikes efficiently without manual intervention.Automated Minimize operational overhead.Why Option A is the best choice:EC2 Auto ScalingAutomatically scales in/out based on demand (e.g., using a scheduled scaling policy for predictable peaks). Ensures fault tolerance by distributing instances across Availability Zones (AZs). Cost-effective Only pays for instances when needed (scales down during idle periods).No manual intervention Fully automated scaling.Why the other options are incorrect:B. Purchase Reserved Instances for peak capacityExpensive Reserved Instances require upfront payment for long-term commitment, even when instances are idle.Wasteful Pays for unused capacity outside peak hours.Not fault-tolerant Reserved Instances alone do not ensure high availability.C. Use a cron job to stop instances during low trafficNot fault-tolerant Stopping instances reduces availability (no instances running during idle periods). Manual scaling required Must restart instances before peaks (risk of delays or failures). Not ideal for web servers Web servers should remain available even with low traffic.D. Use a script to vertically scale instances during peaksLimited scalability Vertical scaling (changing instance size) has limits and may not handle sudden spikes.Not fault-tolerant A single larger instance is a single point of failure. More expensive Larger instances cost more than multiple smaller ones (horizontal scaling is often cheaper).Comparison Table:OptionCost-EffectivenessFault ToleranceScalabilityAutomationBest For A(Pays only for needed capacity)(Multi-AZ deployment)(Horizontal scaling)(Auto Scaling)Predictable traffic spikesB (Overpays for idle capacity) (Single instance type) (Static capacity) (Manual)Long-term steady workloads C (No cost savings if instances must restart) (Instances stopped) (Manual scaling)(Cron job)Non-critical batch jobsD (Larger instances cost more) (Single instance risk) (Vertical limits)(Script)Small-scale, variable workloads Conclusion:Option A is the most cost-effective and fault-tolerant solution because:Auto Scaling dynamically adjusts capacity to match demand (scaling up for peaks, down for idle periods). Ensures high availability by distributing instances across AZs.Minimizes costs by avoiding over-provisioning.Avoid Options B, C, and D (they are either too expensive, lack fault tolerance, or require manual intervention).