SAP-C02 Continuous Improvement for Existing Solutions Practice Question

A company runs a static website on Amazon S3 behind Amazon CloudFront. The website uses a custom domain and SSL certificate from AWS Certificate Manager (ACM). Users report that they sometimes see an older version of the website after updates. What should the company do to ensure users always see the latest content?

⚠ Common exam trap

SAP-C02 often tests the misconception that changing origin-side settings (versioning, TTLs, or toggling the distribution) refreshes edge caches, when only an explicit CloudFront invalidation purges cached objects.

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 CloudFront invalidation for the updated files.

CloudFront caches objects at edge locations based on TTL and only re-fetches from the S3 origin when the cache expires or is explicitly invalidated. When a static site is updated, existing cached copies at edge locations continue to be served until they expire, which is why users sometimes see stale content. Creating a CloudFront invalidation for the updated files (or a wildcard path like /*) forces the edge locations to discard the cached objects and retrieve the latest versions from S3 on the next request.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Disable and re-enable the CloudFront distribution after each update.
Why it's wrong here
Disabling and re-enabling a distribution takes many minutes to redeploy to all edge locations and does not purge cached objects, so stale content persists. It is tempting as a forceful reset, and suits recovering a distribution from a failed state rather than refreshing content.
✗
Enable S3 bucket versioning and use version IDs in URLs.
Why it's wrong here
Versioning retains old object versions but CloudFront still serves whatever key the URL requests; version IDs in URLs change every update and break stable links. It is tempting because versioning protects against overwrites, and suits rollback or accidental-deletion recovery, not cache freshness.
✗
Reduce the CloudFront TTL to 0 seconds for all objects.
Why it's wrong here
A zero TTL forces CloudFront to revalidate every object on every request, adding origin latency and cost without invalidating objects already cached at edge locations or in browsers. It is tempting as a blanket freshness guarantee, and suits rapidly changing APIs where caching is undesirable.
✓
Create a CloudFront invalidation for the updated files.
Why this is correct
CloudFront caches objects at edge locations until the TTL expires, so updated S3 objects can still serve stale copies. An invalidation forces edge locations to fetch the current object from the origin, satisfying the requirement that users always see the latest content.

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

SAP-C02 Continuous Improvement for Existing Solutions Practice Question

Why each option matters

Option-by-option breakdown

AWS S3 Storage Class Comparison

Related to this question