This PCA practice question tests your understanding of design for security and compliance. 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 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?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "least"
Why it matters: You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
roles/storage.objectAdmin
Why wrong: ObjectAdmin provides full control over objects, too permissive.
roles/storage.objectCreator
Why wrong: ObjectCreator allows creation but not read.
roles/storage.admin
Why wrong: Storage admin includes full management, too permissive.
roles/storage.objectViewer
ObjectViewer grants read-only access to objects.
Answer choices
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
The roles/storage.objectViewer role grants read access to objects without listing or other permissions. Option A is too broad (project-level). Option C allows listing but is more than read-only. Option D includes identity and access management permissions.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
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
ObjectAdmin provides full control over objects, too permissive.
roles/storage.objectCreator
Why it's wrong here
ObjectCreator allows creation but not read.
roles/storage.admin
Why it's wrong here
Storage admin includes full management, too permissive.
roles/storage.objectViewer
Why this is correct
ObjectViewer grants read-only access to objects.
Clue confirmation
The clue word "least" in the question point toward this answer.
Related concept
Authentication checks who the user is.
Common exam traps
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related PCA questions on access control and AAA configuration.
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FAQ
Design for security and compliance — This question tests Design for security and compliance — Authentication checks who the user is..
The correct answer is: roles/storage.objectViewer — The roles/storage.objectViewer role grants read access to objects without listing or other permissions. Option A is too broad (project-level). Option C allows listing but is more than read-only. Option D includes identity and access management permissions.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related PCA questions on access control and AAA configuration.
Yes — watch for: "least". You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
Authentication checks who the user is.
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Last reviewed: Jun 24, 2026
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