DVA-C02 Troubleshooting and Optimization Practice Question
A developer is troubleshooting a CloudFront distribution that serves static content from an S3 bucket. Users in some geographic locations report slow load times. The developer checks the CloudFront metrics and sees a high number of cache misses. What is the MOST likely cause?
⚠ Common exam trap
DVA-C02 often tests the confusion between cache misses and latency causes — candidates blame Price Class or compression for high miss rates, when the real driver is a TTL of 0 or a no-cache origin header.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The object TTL is set to a very low value (e.g., 0 seconds).
A very low or zero TTL (e.g., 0 seconds) causes CloudFront to treat every request as a cache miss, forcing it to fetch the object from S3 on each request. This increases latency for users, especially in distant geographic locations, because the edge location must repeatedly retrieve the object from the origin. Setting a reasonable TTL allows edge locations to serve cached content and reduces origin fetches.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The CloudFront distribution is configured with Price Class 100, which uses only the US and Europe edge locations.
Why it's wrong here
Configuring a CloudFront distribution with Price Class 100 restricts its operation to a subset of edge locations, primarily those in North America and Europe. While this choice can lead to increased latency for users located outside these designated regions, as their requests must travel further to reach an available edge, it does not inherently cause cache misses. Once an object is cached at an eligible edge location, subsequent requests to that same location will be served from the cache, irrespective of the price class.
- ✗
The S3 bucket is configured with signed URLs for access.
Why it's wrong here
Configuring an S3 bucket with signed URLs primarily serves as an access control mechanism, granting temporary, authenticated access to private content. While signed URLs often include unique query string parameters that could potentially bypass CloudFront's cache if not properly configured to be part of the cache key, their fundamental purpose is authorization, not preventing caching. The mere presence of signed URLs does not directly cause a high cache miss ratio unless the caching policy is misconfigured to treat each unique signed URL as a distinct object.
- ✗
The CloudFront distribution is not configured to compress objects.
Why it's wrong here
The absence of object compression in a CloudFront distribution means that files are delivered to end-users in their original, uncompressed size. While this can lead to increased bandwidth consumption and slower download times for users, especially over slower network connections, it does not directly impact CloudFront's ability to cache the object. Compression is a delivery optimization, not a cache invalidation or bypass mechanism; the object is still cached, just in a larger format.
- ✓
The object TTL is set to a very low value (e.g., 0 seconds).
Why this is correct
Setting an object's Time To Live (TTL) to a very low value, such as 0 seconds, explicitly instructs CloudFront to either not cache the object at all or to revalidate it with the origin for virtually every subsequent request. This configuration directly prevents CloudFront from effectively serving content from its edge caches, forcing each user request to reach the origin. Consequently, this results in a consistently high cache miss ratio, significantly degrading performance and increasing origin load.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
This DVA-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DVA-C02 exam.