The correct answer is to create a dedicated service account with minimal permissions and attach it to the Compute Engine instance. This approach directly implements the principle of least privilege, ensuring the application authenticates to Cloud Storage using only the specific roles it needs—such as roles/storage.objectViewer—rather than relying on the default Compute Engine service account, which typically carries excessive, broad-scope permissions across multiple Google Cloud services. On the Google Professional Cloud Developer exam, this scenario tests your understanding of secure identity management for production workloads, often appearing as a trap where candidates mistakenly believe the default service account is acceptable for production. The key distinction is that default credentials are convenient for development but violate security best practices in production by increasing the attack surface. Remember the mnemonic "Dedicated and Scoped" to recall that a dedicated service account with scoped permissions is always safer than the default.
PCD Building and testing applications Practice Question
This PCD practice question tests your understanding of building and testing applications. 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.
During a code review, a developer notices that the application's Cloud Storage client library is using the default credentials of the Compute Engine instance. What is a more secure alternative for a production environment?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a dedicated service account with minimal permissions and attach it to the instance
Option A is correct because creating a dedicated service account with minimal permissions and attaching it to the Compute Engine instance follows the principle of least privilege. This avoids using the overly permissive default Compute Engine service account, which often has broad access to many Google Cloud services. By scoping the service account to only the required Cloud Storage permissions (e.g., roles/storage.objectViewer), you reduce the attack surface and adhere to production security best practices.
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.
✓
Create a dedicated service account with minimal permissions and attach it to the instance
Why this is correct
This follows the principle of least privilege and avoids using default credentials.
Related concept
Read the scenario before looking for a memorised answer.
✗
Store user credentials in a configuration file
Why it's wrong here
User credentials are not intended for applications and pose a security risk.
✗
Use an API key for Cloud Storage
Why it's wrong here
API keys are less secure and not recommended for server-to-server communication.
✗
Generate an access token and embed it in the code
Why it's wrong here
Hardcoding tokens is insecure; tokens also expire and need rotation.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that the default Compute Engine service account is acceptable for production, when in fact it is overly permissive and should be replaced with a custom service account scoped to the minimum required roles.
Detailed technical explanation
How to think about this question
Under the hood, the default Compute Engine service account is automatically granted the `roles/iam.serviceAccountUser` and often `roles/editor` on the project, which is far too broad for a storage-only workload. A dedicated service account should be created with the minimal IAM role (e.g., `roles/storage.objectAdmin`) and attached to the instance via the `--service-account` flag during instance creation or by modifying the instance metadata. The client library then uses the instance metadata server (169.254.169.254) to obtain OAuth 2.0 tokens scoped to that service account, ensuring credentials are never stored on disk and are automatically rotated every hour.
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 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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Building and testing applications — This question tests Building and testing applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a dedicated service account with minimal permissions and attach it to the instance — Option A is correct because creating a dedicated service account with minimal permissions and attaching it to the Compute Engine instance follows the principle of least privilege. This avoids using the overly permissive default Compute Engine service account, which often has broad access to many Google Cloud services. By scoping the service account to only the required Cloud Storage permissions (e.g., roles/storage.objectViewer), you reduce the attack surface and adhere to production security best practices.
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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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.
Question Discussion
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