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Difficulty: MediumEdge Caching and Content Delivery for Resilient Architectures

A software publisher distributes installer packages globally. The primary files are stored in an Amazon S3 bucket in the us-west-2 Region, and a backup replica is maintained in an S3 bucket in the eu-central-1 Region. The publisher requires a content delivery solution that ensures high availability and low latency for downloads, even if the primary S3 bucket becomes temporarily unavailable. The solution must minimize operational overhead. Which configuration should a solutions architect recommend to meet these requirements?

  1. A
    Configure Amazon Route 53 with latency-based routing policies pointing to both Amazon S3 buckets. Attach Route 53 health checks to the S3 bucket endpoints to enable automatic failover to the secondary region if the primary bucket is unhealthy.
  2. Configure an Amazon CloudFront distribution with an origin group containing the primary S3 bucket as the primary origin and the backup S3 bucket as the secondary origin. Configure origin failover based on specific HTTP status codes such as 500, 502, 503, or 504.Answer
  3. C
    Configure an Amazon CloudFront distribution with the primary S3 bucket as the origin. Configure AWS WAF with custom rules to monitor origin health and dynamically rewrite requests to point to the backup S3 bucket if the primary bucket is unreachable.
  4. D
    Configure an Amazon CloudFront distribution with the primary S3 bucket as the origin. Set the default Time to Live (TTL) values to 0 seconds on all cache behaviors to force CloudFront to query a Route 53 active-passive failover record set on every client request.

Answer

Configure an Amazon CloudFront distribution with an origin group containing the primary S3 bucket as the primary origin and the backup S3 bucket as the secondary origin. Configure origin failover based on specific HTTP status codes such as 500, 502, 503, or 504.
The correct configuration utilizes Amazon CloudFront origin groups to achieve both low-latency content delivery and high availability. By grouping the primary Amazon S3 bucket (in us-west-2) and the backup S3 bucket (in eu-central-1) into an origin group, CloudFront can automatically fail over to the backup origin when the primary origin returns specific HTTP status codes (such as 500, 502, 503, or 504). This provides seamless, resilient content delivery with minimal latency and zero manual intervention or complex routing overhead.

Step-by-Step Solution

1
Identify the performance and availability requirements.
The solution requires low latency for global downloads (implying the use of a CDN like Amazon CloudFront) and high availability (implying multi-region storage failover).
CloudFront reduces latency by caching content at edge locations close to users, and S3 provides resilient storage across multiple regions.
2
Evaluate the mechanism for automatic failover under CloudFront.
Select Amazon CloudFront Origin Groups as the correct architectural feature to bind the two S3 buckets.
Origin Groups allow a primary and secondary origin to be grouped together, automatically failing over to the secondary origin if the primary origin returns configured HTTP error status codes.
3
Eliminate configurations that introduce high latency or misuse service scopes.
Discard Route 53 direct routing (no caching), AWS WAF routing (incorrect service scope), and setting TTL to 0 (bypasses caching).
These alternatives fail to meet the performance requirement or misapply AWS service capabilities.

Key Concept

Amazon CloudFront Origin Groups and Origin Failover
Estimated Time:1m 30s
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Topics

Edge Caching and Content Delivery for Resilient Architectures

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