SAA-C03 Design High-Performing Architectures Practice Question
Exhibit
CloudFront behavior summary for path pattern /static/*: - Allowed methods: GET, HEAD - Cache policy: forwards all query strings - Origin request policy: forwards all cookies and the Authorization header - Average cache hit ratio: 11% Sample request log lines: GET /static/app.js?v=18&userId=123 Cookie: session=abcd GET /static/app.js?v=18&userId=987 Cookie: session=xyzt GET /static/logo.svg?v=18&locale=en Cookie: session=mnop Origin responses: - All objects are identical for every viewer - Objects are versioned only by the v query parameter
Based on the exhibit, which change will most improve the CloudFront cache hit ratio for the static assets while still serving the same files to all users?
⚠ Common exam trap
Many exam-takers assume increasing TTL or enabling Origin Shield will fix a low cache hit ratio, when the real issue is cache key fragmentation caused by forwarding all cookies and query strings.
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
✓
Create a custom cache policy that includes only the v query string and excludes cookies.
Static assets (e.g., images, CSS, JS) are typically served identically to all users, so forwarding a unique query string like 'v' for versioning still allows CloudFront to cache a single object per version. By excluding cookies and other query strings, you prevent cache fragmentation caused by irrelevant variations, directly improving the cache hit ratio. This custom cache policy ensures that requests for the same 'v' value are served from the edge cache rather than forwarded to the origin.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Create a custom cache policy that includes only the v query string and excludes cookies.
Why this is correct
This removes unnecessary cache-key fragmentation. Since all users receive identical static files, forwarding user-specific cookies and irrelevant query strings destroys cache reuse. Keeping only the version parameter preserves correct object variation while allowing many more requests to hit the same cached object at the edge.
- ✗
Enable Origin Shield and keep the current cache behavior unchanged.
Why it's wrong here
Origin Shield can reduce origin load after a miss, but it does not fix a cache key that is fragmented by unnecessary request data.
When this WOULD be correct
When the question asks for reducing origin load or improving latency for a backend with high request rates, and the current cache behavior already has a high hit ratio.
- ✗
Move the static assets to individual presigned URLs for each viewer.
Why it's wrong here
Presigned URLs are for controlled access, not for improving cache efficiency when the content itself is identical for everyone.
When this WOULD be correct
This option would be correct in a scenario where you need to restrict access to static assets to only authenticated users, such as for a paid content delivery system, and you want to ensure each viewer has a unique, time-limited URL.
- ✗
Increase the CloudFront default TTL to 24 hours while continuing to forward all cookies and query strings.
Why it's wrong here
A longer TTL helps only after a cacheable object is identified; forwarding user-specific data still creates too many distinct cache entries.
When this WOULD be correct
If the question asked for improving cache hit ratio for dynamic content that varies by user session (e.g., personalized pages) and the static assets are served from a different origin or path, increasing TTL while forwarding all cookies/query strings could be correct for the dynamic content.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The SAA-C03 exam frequently reuses these exact scenarios with slightly different constraints.
✓Create a custom cache policy that includes only the v query string and excludes cookies.Correct answer▾
Why this is correct
This removes unnecessary cache-key fragmentation. Since all users receive identical static files, forwarding user-specific cookies and irrelevant query strings destroys cache reuse. Keeping only the version parameter preserves correct object variation while allowing many more requests to hit the same cached object at the edge.
✗Enable Origin Shield and keep the current cache behavior unchanged.Wrong answer — click to see why▾
Why this is wrong here
Enabling Origin Shield reduces origin load and improves latency but does not affect the cache hit ratio when query strings and cookies are still forwarded, as they cause cache fragmentation.
★ When this WOULD be the correct answer
When the question asks for reducing origin load or improving latency for a backend with high request rates, and the current cache behavior already has a high hit ratio.
Why candidates choose this
Candidates may think Origin Shield improves caching because it centralizes requests, but it does not address the root cause of low cache hit ratio: unnecessary query string and cookie forwarding.
✗Move the static assets to individual presigned URLs for each viewer.Wrong answer — click to see why▾
Why this is wrong here
Using presigned URLs for static assets would not improve cache hit ratio because each presigned URL is unique per viewer, preventing CloudFront from caching and serving the same object to multiple users.
★ When this WOULD be the correct answer
This option would be correct in a scenario where you need to restrict access to static assets to only authenticated users, such as for a paid content delivery system, and you want to ensure each viewer has a unique, time-limited URL.
Why candidates choose this
Candidates may think presigned URLs can improve performance by controlling access, but they overlook that uniqueness per viewer defeats caching, which is the opposite of what is needed to improve cache hit ratio.
✗Increase the CloudFront default TTL to 24 hours while continuing to forward all cookies and query strings.Wrong answer — click to see why▾
Why this is wrong here
Forwarding all cookies and query strings prevents CloudFront from caching responses effectively because each unique combination creates a separate cache entry, reducing the cache hit ratio.
★ When this WOULD be the correct answer
If the question asked for improving cache hit ratio for dynamic content that varies by user session (e.g., personalized pages) and the static assets are served from a different origin or path, increasing TTL while forwarding all cookies/query strings could be correct for the dynamic content.
Why candidates choose this
Candidates may think that increasing TTL always improves cache hit ratio, overlooking that forwarding all cookies and query strings negates the benefit by creating many cache variations.
Analysis generated from the official SAA-C03blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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