Google PCA Design for security and compliance Practice Question
A data scientist needs read-only access to a Cloud Storage bucket containing training data. What is the least privileged IAM role to grant at the bucket level?
⚠ Common exam trap
Test-takers frequently confuse roles/storage.objectViewer with roles/storage.objectAdmin or roles/storage.admin, mistakenly thinking broader roles are needed for read access, or they incorrectly assume roles/storage.objectCreator provides read capabilities.
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
✓
roles/storage.objectViewer
Roles/storage.objectViewer grants read-only access to objects in a Cloud Storage bucket without allowing any write or administrative actions. This is the least privileged role that satisfies the requirement for read-only access to training data at the bucket level, as it only permits storage.objects.get and storage.objects.list permissions.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
roles/storage.objectAdmin
Why it's wrong here
roles/storage.objectAdmin grants full control over objects, including create, delete and overwrite, so it breaches least privilege for read-only training data. It is tempting because it is genuinely the right bucket-level role when a principal must manage objects, such as a pipeline that writes and deletes outputs.
- ✗
roles/storage.objectCreator
Why it's wrong here
Object Creator permits uploading new objects but not reading existing ones, so the scientist could not access the training data at all. It suits write-only ingestion pipelines; read-only access to a bucket requires roles/storage.objectViewer instead.
- ✗
roles/storage.admin
Why it's wrong here
Storage Admin grants full control over objects and buckets, including delete and IAM policy changes, far beyond read-only. It is tempting as a broad working role, but the least-privilege fit for reading training data is roles/storage.objectViewer, which permits only list and get.
- ✓
roles/storage.objectViewer
Why this is correct
roles/storage.objectViewer grants read-only access to objects within a bucket, including listing and getting them, without write or delete permissions. Applied at bucket level it satisfies the least-privilege requirement for reading training data, unlike broader roles such as objectAdmin or storageAdmin.
Go deeper
Related to this question
Learn chapter
Data Migration and Transfer Services
Key term
IAM role
An IAM role is a set of permissions that an entity can assume temporarily to access cloud resources securely.
Key term
Least privilege
Least privilege is a security principle that means giving users, systems, or programs only the minimum permissions they need to do their job and nothing more.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.