- A
Gradually shift traffic to the new revision using the gcloud run services update-traffic command.
Correct. Traffic shifting allows incremental rollout and monitoring.
- B
Create a new Cloud Run service for the new revision.
Why wrong: Incorrect. This would create a separate service, not a rolling update within the same service.
- C
Deploy the new revision with the --no-traffic flag.
Correct. This creates the revision without serving traffic, enabling safe rollback.
- D
Set the min-instances attribute to 1 to keep at least one instance running.
Why wrong: Incorrect. This prevents cold starts but does not contribute to zero-downtime deployment.
- E
Use the gcloud run deploy command with the --concurrency flag.
Why wrong: Incorrect. Concurrency controls how many requests a container can handle, not deployment strategy.
PCD Deploying applications Practice Question
This PCD practice question tests your understanding of deploying applications. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 deploys a containerized application to Cloud Run using Cloud Build. They want to implement a rolling update strategy with zero downtime. Which two actions should they take? (Choose two.)
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
Gradually shift traffic to the new revision using the gcloud run services update-traffic command.
Option A is correct because the `gcloud run services update-traffic` command allows you to gradually shift traffic from the current revision to a new revision, enabling a rolling update with zero downtime. This command supports percentage-based traffic splitting, which ensures that the new revision is incrementally exposed to users while the old revision remains active, thus maintaining service availability throughout the deployment.
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.
- ✓
Gradually shift traffic to the new revision using the gcloud run services update-traffic command.
Why this is correct
Correct. Traffic shifting allows incremental rollout and monitoring.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Create a new Cloud Run service for the new revision.
Why it's wrong here
Incorrect. This would create a separate service, not a rolling update within the same service.
- ✓
Deploy the new revision with the --no-traffic flag.
Why this is correct
Correct. This creates the revision without serving traffic, enabling safe rollback.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Set the min-instances attribute to 1 to keep at least one instance running.
Why it's wrong here
Incorrect. This prevents cold starts but does not contribute to zero-downtime deployment.
- ✗
Use the gcloud run deploy command with the --concurrency flag.
Why it's wrong here
Incorrect. Concurrency controls how many requests a container can handle, not deployment strategy.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that `min-instances` or `--concurrency` flags are involved in traffic management or rolling updates, when in fact they only control instance lifecycle and concurrency limits, not traffic routing.
Detailed technical explanation
How to think about this question
Cloud Run uses revision-based traffic routing, where each deployment creates a new revision and traffic can be split between revisions using the `gcloud run services update-traffic` command with the `--to-revisions` flag. The `--no-traffic` flag in option C is correct because it deploys the new revision without immediately routing traffic to it, allowing you to verify the revision before gradually shifting traffic; this two-step process (deploy with `--no-traffic`, then update traffic) is the standard pattern for zero-downtime rolling updates. Under the hood, Cloud Run leverages Google's global load balancer and Knative serving to manage revision routing, ensuring that traffic migration is atomic and does not drop requests.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this PCD question test?
Deploying applications — This question tests Deploying applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Gradually shift traffic to the new revision using the gcloud run services update-traffic command. — Option A is correct because the `gcloud run services update-traffic` command allows you to gradually shift traffic from the current revision to a new revision, enabling a rolling update with zero downtime. This command supports percentage-based traffic splitting, which ensures that the new revision is incrementally exposed to users while the old revision remains active, thus maintaining service availability throughout the deployment.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This PCD practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCD exam.
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