AWS Certified Solutions Architect - Associate

Explanation

Correct Answer: C - Use dynamic scaling to change the size of the Auto Scaling group.

Why dynamic scaling is the most cost-effective solution:

1. Handles unpredictable traffic patterns: The question states that traffic increases occur on "random days of the week," making them unpredictable. Dynamic scaling responds to real-time metrics (like CPU utilization, request count, etc.) to scale up or down automatically.

2. Cost-effective scaling: Dynamic scaling ensures you only scale up when needed (during traffic spikes) and scale down when traffic subsides, optimizing costs by not over-provisioning resources.

3. Automatic response: Unlike manual scaling, dynamic scaling doesn't require human intervention, allowing immediate response to traffic spikes.

Analysis of other options:

• A. Manual scaling: Not cost-effective because it requires human intervention, which may not be timely enough for sudden traffic spikes. Also, it's inefficient for random, unpredictable patterns.

• B. Predictive scaling: Uses machine learning to forecast traffic patterns, but this works best for predictable, recurring patterns (like daily/weekly cycles). Since traffic spikes are "random," predictive scaling may not accurately forecast them.

• D. Schedule scaling: Works for predictable, scheduled events (like business hours or known events). Since traffic spikes are "random days of the week," schedule scaling cannot effectively handle this scenario.

Key AWS Concepts:

• Dynamic scaling: Uses CloudWatch alarms and scaling policies to automatically add/remove instances based on real-time metrics.
• Predictive scaling: Uses machine learning to forecast traffic and pre-scale before anticipated demand.
• Schedule scaling: Scales based on predetermined schedules.
• Manual scaling: Human-initiated scaling changes.

For unpredictable, sudden traffic increases, dynamic scaling provides the most cost-effective and responsive solution.