Quick Answer
The answer is Cloud IAM, as it is the foundational service for authenticating and authorizing service accounts when you need to programmatically create and manage Compute Engine instances. Cloud IAM provides the identity and access management framework that issues OAuth 2.0 tokens for authentication and enforces role-based access control (RBAC) for authorization, meaning you attach a service account to your Compute Engine resources and grant it specific IAM roles like roles/compute.instanceAdmin to define permitted actions. On the Google Professional Cloud Architect exam, this question tests your understanding that authentication and authorization are IAM responsibilities, not Compute Engine’s—a common trap is confusing the Compute Engine API (which handles instance creation) with IAM (which controls who can call that API). Remember the memory tip: “IAM is the gatekeeper; Compute Engine is the builder.”
This PCA practice question tests your understanding of manage and provision cloud infrastructure. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 developer needs to programmatically create and manage Compute Engine instances. Which Google Cloud service should they use to authenticate and authorize service accounts?
Cloud Audit Logs
Why wrong: Audit logs record API activities, not authentication.
Cloud Key Management Service (KMS)
Why wrong: KMS manages cryptographic keys, not service accounts.
Cloud Scheduler
Why wrong: Scheduler is for scheduled job execution, not authentication.
Cloud IAM
IAM manages service accounts and permissions.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Cloud IAM
Cloud IAM is the correct service because it provides the identity and access management framework for authenticating and authorizing service accounts. When a developer creates Compute Engine instances, they must attach a service account and grant IAM roles (e.g., roles/compute.instanceAdmin) to define what actions that service account can perform. Cloud IAM handles the authentication via OAuth 2.0 tokens and authorization via role-based access control (RBAC), making it the foundational service for managing service account permissions.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Cloud Audit Logs
Why it's wrong here
Audit logs record API activities, not authentication.
Cloud Key Management Service (KMS)
Why it's wrong here
KMS manages cryptographic keys, not service accounts.
Cloud Scheduler
Why it's wrong here
Scheduler is for scheduled job execution, not authentication.
Cloud IAM
Why this is correct
IAM manages service accounts and permissions.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Google Cloud often tests the misconception that Cloud Audit Logs or Cloud KMS can handle authentication/authorization, but candidates must remember that only Cloud IAM manages identities and permissions, while the other options serve logging or encryption purposes.
Detailed technical explanation
Under the hood, when a Compute Engine instance is created with a service account, the instance's metadata server provides OAuth 2.0 access tokens scoped to the IAM roles granted to that service account. These tokens are used to authenticate API calls to Google Cloud services, and the token's validity is verified by the IAM system using the service account's unique ID and the roles assigned via IAM policies. A real-world scenario is a CI/CD pipeline that uses a service account with roles/compute.instanceAdmin.v1 to programmatically create instances; without proper IAM roles, the API call would fail with a 403 Forbidden error.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
Manage and provision cloud infrastructure — This question tests Manage and provision cloud infrastructure — Read the scenario before looking for a memorised answer..
The correct answer is: Cloud IAM — Cloud IAM is the correct service because it provides the identity and access management framework for authenticating and authorizing service accounts. When a developer creates Compute Engine instances, they must attach a service account and grant IAM roles (e.g., roles/compute.instanceAdmin) to define what actions that service account can perform. Cloud IAM handles the authentication via OAuth 2.0 tokens and authorization via role-based access control (RBAC), making it the foundational service for managing service account permissions.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This PCA 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 PCA exam.
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