AWS Certified Cloud Practitioner

Explanation

High availability and fault tolerance require distributing resources across multiple independent failure domains to ensure continued operation even if one component fails.

Why Option B is Correct:

• Availability Zones (AZs) are physically separate data centers within an AWS Region
• Each AZ has independent power, cooling, and networking
• Deploying across multiple AZs ensures that if one AZ fails, the application can continue running in other AZs
• This provides automatic failover and redundancy

Why Other Options Are Incorrect:

• Option A (Single AZ): Vulnerable to AZ-level failures - if that single AZ goes down, the entire application becomes unavailable
• Option C (Multiple subnets in one AZ): While subnets provide network segmentation, they still share the same physical infrastructure within one AZ, so they're vulnerable to AZ-level failures
• Option D (Edge locations with Outposts): AWS Outposts extend AWS infrastructure to on-premises locations, but edge locations are primarily for content delivery (CloudFront) and don't provide the same level of high availability as multi-AZ deployments

Key AWS Concepts:

• Availability Zones: Isolated locations within AWS Regions
• High Availability: System's ability to remain operational for extended periods
• Fault Tolerance: System's ability to continue operating despite component failures

For maximum resilience, AWS recommends deploying critical applications across multiple Availability Zones.