The answer is that CloudFront cache invalidation after S3 sync in CodePipeline is the missing step, because CloudFront caches the old content at edge locations and continues serving it even after the S3 bucket is updated. When CodePipeline runs an `aws s3 sync` command, it successfully uploads new files to the bucket, but CloudFront does not automatically purge its cached copies—it will keep delivering stale responses until the TTL expires or a manual invalidation is triggered. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of how CDN caching interacts with deployment pipelines; a common trap is assuming that updating the origin alone refreshes the cache. The correct fix is to add a CloudFront invalidation step (e.g., `aws cloudfront create-invalidation`) in the pipeline after the sync. Memory tip: "Sync updates the source, but CloudFront serves the cache—invalidate to innovate."
DOP-C02 SDLC Automation Practice Question
This DOP-C02 practice question tests your understanding of sdlc automation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A company uses AWS CodePipeline to automate the deployment of a static website hosted on Amazon S3. The pipeline includes a source stage that pulls from a CodeCommit repository and a deploy stage that uses CodeBuild to sync the files to an S3 bucket. The team noticed that the website is not updating after a successful pipeline run. The CodeBuild logs show that the 'aws s3 sync' command completed successfully. However, the website still shows the old content. What is the MOST likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
The CodeBuild project does not have permission to write to the S3 bucket.
Why wrong: The logs show the sync completed successfully, so permissions are sufficient.
B
The S3 bucket is not configured for static website hosting.
Why wrong: If the site was working before, the bucket must be configured for hosting.
C
The website is fronted by Amazon CloudFront, which is caching the old content.
CloudFront caches content; a cache invalidation is needed to serve the new files.
D
The S3 bucket policy is blocking public access to the updated objects.
Why wrong: If objects were previously accessible, the bucket policy likely allows public read; the sync command would fail if permissions were an issue.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The website is fronted by Amazon CloudFront, which is caching the old content.
Option B is correct because S3 static website hosting serves content from the bucket, but if CloudFront is used as a CDN, it caches the content. The sync command updates the S3 bucket, but CloudFront serves cached content until the TTL expires or the cache is invalidated. Option A is wrong because the bucket policy does not affect serving content if it's already public. Option C is wrong because the sync command does not require public access to update objects. Option D is wrong because website hosting can be enabled on the bucket; the issue is caching.
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.
✗
The CodeBuild project does not have permission to write to the S3 bucket.
Why it's wrong here
The logs show the sync completed successfully, so permissions are sufficient.
✗
The S3 bucket is not configured for static website hosting.
Why it's wrong here
If the site was working before, the bucket must be configured for hosting.
✓
The website is fronted by Amazon CloudFront, which is caching the old content.
Why this is correct
CloudFront caches content; a cache invalidation is needed to serve the new files.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The S3 bucket policy is blocking public access to the updated objects.
Why it's wrong here
If objects were previously accessible, the bucket policy likely allows public read; the sync command would fail if permissions were an issue.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Trap categories for this question
Command / output trap
The logs show the sync completed successfully, so permissions are sufficient.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which DOP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
SDLC Automation — This question tests SDLC Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The website is fronted by Amazon CloudFront, which is caching the old content. — Option B is correct because S3 static website hosting serves content from the bucket, but if CloudFront is used as a CDN, it caches the content. The sync command updates the S3 bucket, but CloudFront serves cached content until the TTL expires or the cache is invalidated. Option A is wrong because the bucket policy does not affect serving content if it's already public. Option C is wrong because the sync command does not require public access to update objects. Option D is wrong because website hosting can be enabled on the bucket; the issue is caching.
What should I do if I get this DOP-C02 question wrong?
Identify which DOP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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