The answer is to grant the custom service account the Cloud KMS CryptoKey Decrypter role. This is required because Vertex AI Training uses the custom service account as its identity when accessing resources, and CMEK encryption in Vertex AI Training with a custom service account means the Cloud Storage data is locked with a key that only authorized identities can use. Even if the service account has Storage Object Viewer permissions, it cannot decrypt the encrypted objects without the Cloud KMS CryptoKey Decrypter role, which allows it to use the key to decrypt the data at rest. On the Google Professional Machine Learning Engineer exam, this tests your understanding of how IAM and KMS permissions intersect with Vertex AI’s execution context—a common trap is assuming Storage permissions alone suffice. Remember: the service account must be a key decrypter, not just a data viewer. Memory tip: “To train on CMEK, decrypt the key—not just see the bucket.”
PMLE Collaborating to manage data and models Practice Question
This PMLE practice question tests your understanding of collaborating to manage data and models. 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 healthcare startup is developing a diagnostic model using sensitive patient data. They use Vertex AI to manage the training pipeline. They need to ensure that the data is encrypted both at rest and in transit. Additionally, they want to prevent the ML engineers from seeing raw data but still allow them to train models. They use Cloud Storage with CMEK and VPC-SC. They plan to use Vertex AI Training with a custom service account. The data stored in Cloud Storage is encrypted with CMEK. What additional step is needed to allow Vertex AI Training to access the encrypted data?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Grant the custom service account the Cloud KMS CryptoKey Decrypter role.
The correct answer is D because Vertex AI Training must use a custom service account that has the Cloud KMS CryptoKey Decrypter role to decrypt the CMEK-encrypted data stored in Cloud Storage. The custom service account is the identity that Vertex AI jobs run as, and it needs explicit permission to decrypt the CMEK key to read the training data. Without this role, the encrypted objects remain inaccessible even if the service account has Storage Object Viewer permissions.
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.
✗
Use a service account with the 'Storage Admin' role and 'Cloud KMS CryptoKey Decrypter' role.
Why it's wrong here
Storage Admin is overly permissive; only decrypt is needed.
✗
Grant the Cloud Storage service agent the Cloud KMS CryptoKey Decrypter role.
Why it's wrong here
The service agent is used when Cloud Storage needs to access KMS, but for training, the compute service account needs access.
✗
Disable encryption for the training data to simplify access.
Grant the custom service account the Cloud KMS CryptoKey Decrypter role.
Why this is correct
The custom service account used by Vertex AI Training must have decrypt permission to read CMEK-encrypted data.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the Cloud Storage service agent (used for default encryption) with the custom service account that Vertex AI jobs use, leading them to incorrectly grant permissions to the wrong principal.
Detailed technical explanation
How to think about this question
CMEK (Customer-Managed Encryption Keys) in Cloud Storage uses Cloud KMS to wrap data encryption keys (DEKs). When a service account reads an encrypted object, Cloud Storage sends a decrypt request to Cloud KMS using the service account's identity. The service account must have the 'cloudkms.cryptoKeyVersions.useToDecrypt' permission (granted via the Cloud KMS CryptoKey Decrypter role) on the specific key. Vertex AI Training jobs run under a user-specified custom service account, so that account must be granted this role on the CMEK key used to encrypt the Cloud Storage bucket or objects.
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.
Collaborating to manage data and models — This question tests Collaborating to manage data and models — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Grant the custom service account the Cloud KMS CryptoKey Decrypter role. — The correct answer is D because Vertex AI Training must use a custom service account that has the Cloud KMS CryptoKey Decrypter role to decrypt the CMEK-encrypted data stored in Cloud Storage. The custom service account is the identity that Vertex AI jobs run as, and it needs explicit permission to decrypt the CMEK key to read the training data. Without this role, the encrypted objects remain inaccessible even if the service account has Storage Object Viewer permissions.
What should I do if I get this PMLE 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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This PMLE 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 PMLE exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.