- A
Add a Cloud Armor security policy to the Cloud Run service blocking all IPs except Cloud Scheduler.
Why wrong: Cloud Armor cannot be attached directly to Cloud Run services (only to load balancers). Also, Cloud Scheduler doesn't have fixed IP ranges to allowlist.
- B
Disable unauthenticated invocations on the Cloud Run service, grant `roles/run.invoker` to the Scheduler SA, and configure Scheduler to use OIDC authentication.
This three-step configuration enforces authentication: Cloud Run requires auth tokens, the Scheduler SA has invoker permission, and Scheduler sends OIDC tokens with each request. No other caller can invoke the service.
- C
Deploy the Cloud Run service in a VPC and use a VPC firewall rule to block all traffic except Cloud Scheduler.
Why wrong: Cloud Run services are not deployed in a VPC (they use VPC connectors for outbound access). VPC firewall rules don't control inbound access to Cloud Run.
- D
Add a secret header to Cloud Scheduler requests and validate it in the Cloud Run application code.
Why wrong: Custom header validation is a fragile, application-level secret — not a proper authentication mechanism. The secret header could be brute-forced or leaked. OIDC-based IAM authentication is the correct approach.
Quick Answer
The correct answer is to disable unauthenticated invocations on the Cloud Run service, grant the `roles/run.invoker` role to the Cloud Scheduler service account, and configure Scheduler to use OIDC authentication. This works because Cloud Run enforces IAM-based access when unauthenticated invocations are turned off, so only identities with the `run.invoker` role can call the service. By using OIDC authentication, Cloud Scheduler presents a signed Google identity token, which Cloud Run verifies to confirm the request came from a specific scheduler job rather than the public internet. On the Google Associate Cloud Engineer exam, this scenario tests your understanding of service-to-service authorization and the difference between OIDC and basic auth in Scheduler. A common trap is thinking that granting the invoker role alone is enough—you must also explicitly disable unauthenticated access and configure OIDC in the scheduler’s HTTP target. Memory tip: think “Disable, Grant, OIDC” to lock in the three-step sequence.
Google ACE Configuring access and security Practice Question
This ACE practice question tests your understanding of configuring access and security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
You need to ensure that a Cloud Run service can only be invoked by specific Cloud Scheduler jobs and not from the public internet, while still receiving HTTP requests. The Cloud Run service currently allows unauthenticated invocations. What configuration changes are required?
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
Disable unauthenticated invocations on the Cloud Run service, grant `roles/run.invoker` to the Scheduler SA, and configure Scheduler to use OIDC authentication.
Option B is correct because Cloud Run services that require authentication must have unauthenticated invocations disabled, and the Cloud Scheduler service account must be granted the `roles/run.invoker` role. Additionally, Cloud Scheduler must be configured to use OIDC authentication, which allows it to present an identity token signed by Google to the Cloud Run service, ensuring only authorized scheduler jobs can invoke the service.
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.
- ✗
Add a Cloud Armor security policy to the Cloud Run service blocking all IPs except Cloud Scheduler.
Why it's wrong here
Cloud Armor cannot be attached directly to Cloud Run services (only to load balancers). Also, Cloud Scheduler doesn't have fixed IP ranges to allowlist.
- ✓
Disable unauthenticated invocations on the Cloud Run service, grant `roles/run.invoker` to the Scheduler SA, and configure Scheduler to use OIDC authentication.
Why this is correct
This three-step configuration enforces authentication: Cloud Run requires auth tokens, the Scheduler SA has invoker permission, and Scheduler sends OIDC tokens with each request. No other caller can invoke the service.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Deploy the Cloud Run service in a VPC and use a VPC firewall rule to block all traffic except Cloud Scheduler.
Why it's wrong here
Cloud Run services are not deployed in a VPC (they use VPC connectors for outbound access). VPC firewall rules don't control inbound access to Cloud Run.
- ✗
Add a secret header to Cloud Scheduler requests and validate it in the Cloud Run application code.
Why it's wrong here
Custom header validation is a fragile, application-level secret — not a proper authentication mechanism. The secret header could be brute-forced or leaked. OIDC-based IAM authentication is the correct approach.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that IP-based restrictions (like Cloud Armor or VPC firewall rules) can secure serverless services, when in fact serverless services like Cloud Run require IAM-based authentication for secure, identity-aware access control.
Detailed technical explanation
How to think about this question
Under the hood, Cloud Run uses IAM to authorize invocations when unauthenticated access is disabled. The Cloud Scheduler job uses OIDC authentication to generate a Google-signed identity token (JWT) that includes the scheduler's service account email as the `sub` claim. Cloud Run validates this token against the IAM policy, ensuring only the specific service account with `roles/run.invoker` can invoke the service. This mechanism is defined in the Google Cloud IAM and Cloud Run documentation, and it is the only way to restrict access to a specific Cloud Scheduler job without exposing the service to the public internet.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this ACE question test?
Configuring access and security — This question tests Configuring access and security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Disable unauthenticated invocations on the Cloud Run service, grant `roles/run.invoker` to the Scheduler SA, and configure Scheduler to use OIDC authentication. — Option B is correct because Cloud Run services that require authentication must have unauthenticated invocations disabled, and the Cloud Scheduler service account must be granted the `roles/run.invoker` role. Additionally, Cloud Scheduler must be configured to use OIDC authentication, which allows it to present an identity token signed by Google to the Cloud Run service, ensuring only authorized scheduler jobs can invoke the service.
What should I do if I get this ACE 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 30, 2026
This ACE 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 ACE exam.
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