AWS Certified Solutions Architect – Associate (SAA-C03)Design Cost-Optimized ArchitecturesMedium
A media streaming company serves video content to millions of users globally. They use Amazon S3 as the origin for their video files and Amazon CloudFront for content delivery. To minimize egress data transfer costs from S3, which are a major component of their AWS bill, which CloudFront configuration should they prioritize?
- AConfigure CloudFront to use a custom origin instead of S3.
- BEnable CloudFront Field-Level Encryption.
- CEnsure a high cache hit ratio in CloudFront.
- DIncrease the TTL (Time-To-Live) for objects in S3.
Show answer & explanationAnswer & explanation
Correct answer: C. Ensure a high cache hit ratio in CloudFront.
A high cache hit ratio in CloudFront means more requests are served directly from CloudFront's edge locations, significantly reducing the number of times CloudFront has to fetch content from the S3 origin. This directly minimizes egress data transfer from S3, which is billed at a higher rate than CloudFront egress.
Why the other options are wrong
- A. Using a custom origin instead of S3 would still incur egress costs from that origin, and S3 is generally a cost-effective and scalable origin for CloudFront.
- B. Field-Level Encryption is a security feature and has no direct impact on optimizing data transfer costs from S3 to CloudFront or from CloudFront to users.
- D. Increasing TTL in S3 only affects how long S3 caches objects internally or how long clients might cache directly from S3; it doesn't directly control CloudFront's caching behavior or reduce S3 egress costs as effectively as CloudFront's own cache hit ratio.
CloudFront Cache Hit Ratio
The CloudFront cache hit ratio is the percentage of viewer requests that are served directly from CloudFront's edge caches, without forwarding the request to the origin.
- Higher ratio means fewer requests to the origin server (e.g., S3).
- Reduces origin server load and egress data transfer costs.
- Improves content delivery performance for end-users.
- Can be optimized by configuring appropriate TTLs and cache behaviors.
Memory trick: Cache Hits High, Costs Fly Low.