The answer is to create a cache policy that excludes Authorization, cookies, and unnecessary query strings, while narrowing the origin request policy to forward only the headers the S3 origin actually needs. This is correct because versioned JavaScript and CSS files are immutable—each new release changes the filename, so the old files never need revalidation. By aggressively caching these static assets and stripping out variables like query strings and cookies that would otherwise create multiple cache entries for the same object, you maximize the cache hit ratio and drastically reduce origin fetches. On the SAA-C03 exam, this scenario tests your understanding of how CloudFront cache policies differ from origin request policies, with a common trap being to forward all headers “just in case,” which destroys caching efficiency. Remember the memory tip: for versioned static files, treat the cache like a vault—lock it tight by excluding everything the origin doesn’t explicitly need, and your hit ratio will stay high.
SAA-C03 Design Cost-Optimized Architectures Practice Question
This SAA-C03 practice question tests your understanding of design cost-optimized architectures. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
CloudFront behavior summary:
Origin: assets-prod.s3.amazonaws.com
Cache policy: forwards all cookies, all query strings, and the Authorization header
Origin request policy: forwards all headers
Access logs:
x-edge-result-type=Miss: 81%
x-edge-result-type=Hit: 19%
Object names:
/static/app.v18a9f3.js
/static/vendor.v18a9f3.css
Request pattern:
Many requests include Authorization: Bearer <token>
Query strings are used only for analytics and do not affect file content
Based on the exhibit, the team serves versioned JavaScript and CSS files from an S3 origin through CloudFront. After a release, the cache hit ratio dropped and origin fetches increased sharply. What change best reduces both CloudFront and S3 costs without changing the application’s public behavior?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
CloudFront behavior summary:
Origin: assets-prod.s3.amazonaws.com
Cache policy: forwards all cookies, all query strings, and the Authorization header
Origin request policy: forwards all headers
Access logs:
x-edge-result-type=Miss: 81%
x-edge-result-type=Hit: 19%
Object names:
/static/app.v18a9f3.js
/static/vendor.v18a9f3.css
Request pattern:
Many requests include Authorization: Bearer <token>
Query strings are used only for analytics and do not affect file content
A
Increase the CloudFront price class to include more edge locations.
Why wrong: A broader price class can change geographic reach and pricing, but it does not address the real problem: the cache key is fragmented by headers and query strings that do not affect the content of these versioned static assets.
B
Create a cache policy that excludes Authorization, cookies, and unnecessary query strings, and narrow the origin request policy to forward only the headers the S3 origin actually needs.
The hit ratio is low because CloudFront is varying the cache on request attributes that do not change versioned static files. Removing Authorization, cookies, and irrelevant query strings from the cache key allows CloudFront to reuse cached objects across users and sessions. Reducing the origin request policy avoids sending unnecessary viewer context to the origin. Because the filenames are already versioned, long TTLs can be used safely and will lower origin requests and S3 request costs.
C
Disable CloudFront and serve the files directly from S3 to avoid cache invalidation overhead.
Why wrong: Serving directly from S3 removes the caching layer entirely, which increases origin requests and data transfer from S3 while also reducing performance for global users. It would likely increase overall cost rather than reduce it.
D
Use Lambda@Edge to rewrite every request into a unique path so that clients never receive stale files.
Why wrong: Rewriting every request into a unique path fragments the cache further and reduces cache reuse. It also adds compute cost and defeats the purpose of a shared CDN cache for versioned static content.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a cache policy that excludes Authorization, cookies, and unnecessary query strings, and narrow the origin request policy to forward only the headers the S3 origin actually needs.
B is correct because versioned JavaScript and CSS files are immutable, so CloudFront should cache them aggressively. By creating a cache policy that excludes unnecessary headers (like Authorization and cookies) and query strings, and narrowing the origin request policy to forward only required headers, you maximize cache hits and reduce origin fetches. This directly lowers both CloudFront data transfer costs (fewer origin requests) and S3 request costs (fewer GET requests), without altering the application's public behavior.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Increase the CloudFront price class to include more edge locations.
Why it's wrong here
A broader price class can change geographic reach and pricing, but it does not address the real problem: the cache key is fragmented by headers and query strings that do not affect the content of these versioned static assets.
✓
Create a cache policy that excludes Authorization, cookies, and unnecessary query strings, and narrow the origin request policy to forward only the headers the S3 origin actually needs.
Why this is correct
The hit ratio is low because CloudFront is varying the cache on request attributes that do not change versioned static files. Removing Authorization, cookies, and irrelevant query strings from the cache key allows CloudFront to reuse cached objects across users and sessions. Reducing the origin request policy avoids sending unnecessary viewer context to the origin. Because the filenames are already versioned, long TTLs can be used safely and will lower origin requests and S3 request costs.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Disable CloudFront and serve the files directly from S3 to avoid cache invalidation overhead.
Why it's wrong here
Serving directly from S3 removes the caching layer entirely, which increases origin requests and data transfer from S3 while also reducing performance for global users. It would likely increase overall cost rather than reduce it.
✗
Use Lambda@Edge to rewrite every request into a unique path so that clients never receive stale files.
Why it's wrong here
Rewriting every request into a unique path fragments the cache further and reduces cache reuse. It also adds compute cost and defeats the purpose of a shared CDN cache for versioned static content.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think increasing edge locations (Option A) or using Lambda@Edge (Option D) will improve performance, but for versioned static files, the real cost optimization comes from maximizing cache hits by properly configuring cache and origin request policies, not from adding more infrastructure or rewriting requests.
Detailed technical explanation
How to think about this question
CloudFront cache keys are derived from the request's origin, path, query strings, and headers included in the cache policy. By default, CloudFront includes the Authorization header in the cache key, which can cause cache misses if different users send different Authorization values (e.g., signed URLs). For S3 origins serving static files, excluding Authorization, cookies, and unnecessary query strings ensures that all users share the same cached object, maximizing the cache hit ratio. Additionally, the origin request policy controls what headers are forwarded to S3; forwarding only essential headers (like Host) reduces S3 processing overhead and prevents unnecessary invalidation of cached objects.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Design Cost-Optimized Architectures — This question tests Design Cost-Optimized Architectures — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a cache policy that excludes Authorization, cookies, and unnecessary query strings, and narrow the origin request policy to forward only the headers the S3 origin actually needs. — B is correct because versioned JavaScript and CSS files are immutable, so CloudFront should cache them aggressively. By creating a cache policy that excludes unnecessary headers (like Authorization and cookies) and query strings, and narrowing the origin request policy to forward only required headers, you maximize cache hits and reduce origin fetches. This directly lowers both CloudFront data transfer costs (fewer origin requests) and S3 request costs (fewer GET requests), without altering the application's public behavior.
What should I do if I get this SAA-C03 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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