Exams / SAA-C03 / Caching and content delivery / Question 1
SAA-C03 practice question: Caching and content delivery (1 of 3)
Design High-Performing Architectures A free question from our original SAA-C03 practice exam. Try it, then open the answer to see why each option is right or wrong.
A travel publisher stores 2 TB of photos and short videos in an Amazon S3 bucket in the eu-west-2 (London) Region. Most readers are in North America and Asia, and they report slow page loads. The same popular files are requested millions of times a day. Security policy requires the bucket to stay private, with no public objects. The team wants the solution with the LEAST operational overhead. Which solution meets these requirements?
Choose one answer.
- AA. Turn on S3 Transfer Acceleration for the bucket, and serve files to readers through the bucket's accelerate endpoint using presigned URLs.
- BB. Put a CloudFront distribution in front of the bucket, and use origin access control so the bucket policy allows only that distribution.
- CC. Replicate the bucket to buckets in us-east-1 and ap-southeast-1 with S3 Cross-Region Replication, and have the website choose the nearest bucket.
- DD. Run caching proxy servers on EC2 in three Regions behind AWS Global Accelerator, with the proxies reading from the bucket through an IAM role.
Show the answer and explanation
Answer: B
- A. Wrong: Transfer Acceleration routes transfers through edge locations to the bucket over an optimised network path, mainly to speed up long-distance uploads. Every download still comes from the London bucket rather than a nearby cache, and it adds data transfer charges. It does not suit millions of repeat reads. Learn more: Configuring fast, secure file transfers using Amazon S3 Transfer Acceleration (opens in a new tab)
- B. Right: Correct. CloudFront caches popular files at edge locations near readers, so repeat requests no longer cross continents. With origin access control, the bucket policy allows only the CloudFront service principal for that distribution, so the bucket stays private. Learn more: Restrict access to an Amazon S3 origin (opens in a new tab)
- C. Wrong: Copies closer to readers would help latency, but this triples storage, adds replication charges and needs website logic to pick a bucket and sign requests for private objects. Readers far from all three Regions still wait. A CDN gives wider coverage with less to manage. Learn more: Replicating objects within and across Regions (opens in a new tab)
- D. Wrong: This can work, but the team would have to build, patch and scale its own caching fleet in three Regions. Global Accelerator speeds up the network path to endpoints such as load balancers and EC2 instances; it does not cache content itself. CloudFront provides the caching as a managed service. Learn more: Endpoints for standard accelerators in AWS Global Accelerator (opens in a new tab)
Explanation
Repeated downloads of the same files by readers far from the origin Region are what a content delivery network is for. CloudFront caches the files at edge locations worldwide, and origin access control keeps the bucket private by allowing reads only from the distribution. The other options either do not cache, or need the team to run its own replicas or proxies.
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