Why Cloud Deploy Pipeline Fails: Canary Percentages Not Summing to 100
This PCD practice question tests your understanding of building and testing applications. 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.
Refer to the exhibit. The developer receives an error when creating the delivery pipeline. 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 answer is that the canary percentages for the prod target do not sum to 100, which causes the Cloud Deploy pipeline to fail. In Google Cloud Deploy, the canary rollout strategy requires the percentage increments defined for a target to add up exactly to 100, because each value represents a sequential traffic shift ending with full deployment. In the exhibit, the prod stage lists 10, 20, and 60, which sum to only 90, and the final 100 is not an incremental step but the final full rollout—so the increments themselves must total 100. On the Google Professional Cloud Developer exam, this tests your understanding of how Cloud Deploy validates pipeline configurations, and a common trap is mistaking the final 100 as part of the incremental sum. Remember: the increments are the steps before the final 100, and they must always sum to 100—think of it as “the steps to the top must fill the staircase.”
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 canary percentages for the prod target do not sum to 100.
Option C is correct because in a canary deployment pipeline, the percentages assigned to the canary and primary stages must sum to 100% to represent the full traffic split. If they do not sum to 100, the pipeline fails as the deployment service cannot determine how to route the remaining traffic, causing the error.
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 prod target is missing a verification step.
Why it's wrong here
Verification steps are optional for pipeline creation.
✗
The dev target has four percentages, but only two are allowed.
Why it's wrong here
Cloud Deploy allows multiple percentages for canary deployment.
✓
The canary percentages for the prod target do not sum to 100.
Why this is correct
The increments should sum to 100; here they sum to 90, causing validation error.
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 pipeline name is too long.
Why it's wrong here
Cloud Deploy allows long names.
Common exam traps
Common exam trap: answer the scenario, not the keyword
In Google Cloud Deploy, when configuring a canary deployment, the percentages for the canary and primary stages must sum to 100%. Candidates may overlook this validation rule and focus on unrelated details like the number of stages or pipeline name length.
Detailed technical explanation
How to think about this question
In canary deployments, the traffic shift is controlled by specifying percentages for each stage (e.g., canary 10%, primary 90%). The sum must equal 100% to ensure all traffic is accounted for; otherwise, the deployment service (like AWS CodeDeploy or Spinnaker) rejects the configuration. This is enforced at pipeline creation time to prevent undefined routing behavior during the deployment.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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.
Building and testing applications — This question tests Building and testing applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The canary percentages for the prod target do not sum to 100. — Option C is correct because in a canary deployment pipeline, the percentages assigned to the canary and primary stages must sum to 100% to represent the full traffic split. If they do not sum to 100, the pipeline fails as the deployment service cannot determine how to route the remaining traffic, causing the error.
What should I do if I get this PCD 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: "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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