- A
Rely on the default encryption at rest and use VPC Service Controls to limit data exfiltration.
Why wrong: Default encryption does not provide fine-grained access control to disk data.
- B
Use customer-supplied encryption keys (CSEK) and write a startup script to mount encrypted disks.
Why wrong: CSEK is deprecated and does not integrate well with Dataproc's access control.
- C
Enable encryption at rest using Google-managed encryption keys and grant all users the Dataproc Editor role.
Why wrong: Google-managed keys do not allow custom access control; all editors would have access.
- D
Use customer-managed encryption keys (CMEK) for the cluster's persistent disks and assign a dedicated service account to the cluster with minimal IAM roles.
CMEK provides control over keys, and a dedicated service account restricts data access.
Quick Answer
The correct answer is to use customer-managed encryption keys (CMEK) for the cluster’s persistent disks and assign a dedicated service account with minimal IAM roles. This works because CMEK gives you direct control over the encryption keys protecting data at rest on Dataproc’s attached disks, ensuring that even if the underlying infrastructure is compromised, the data remains unreadable without your key. By coupling this with a dedicated service account that has only the permissions required for the job, you enforce least privilege, meaning only that specific identity can access the cluster’s disk data. On the Google Professional Data Engineer exam, this scenario tests your understanding of how encryption and identity intersect in Dataproc—a common trap is assuming default Google-managed keys or the Compute Engine default service account are sufficient, but the question explicitly demands both key control and access restriction. Remember the pairing: CMEK for the “what” (encryption) and a dedicated service account for the “who” (access). A useful mnemonic is “Keys and IDs: lock the disks, limit the tasks.”
PDE Practice Question: Building and operationalizing data processing systems
This PDE practice question tests your understanding of building and operationalizing data processing systems. 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.
An organization uses Cloud Dataproc to run Spark jobs that process sensitive data. They need to ensure data is encrypted at rest and that only specific service accounts can access the data on cluster disks. What should they do?
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
Use customer-managed encryption keys (CMEK) for the cluster's persistent disks and assign a dedicated service account to the cluster with minimal IAM roles.
Option D is correct because using customer-managed encryption keys (CMEK) allows the organization to control and manage the encryption keys for persistent disks attached to the Dataproc cluster, ensuring data at rest is encrypted. Assigning a dedicated service account with minimal IAM roles ensures that only that service account can access the data on the cluster disks, following the principle of least privilege.
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.
- ✗
Rely on the default encryption at rest and use VPC Service Controls to limit data exfiltration.
Why it's wrong here
Default encryption does not provide fine-grained access control to disk data.
- ✗
Use customer-supplied encryption keys (CSEK) and write a startup script to mount encrypted disks.
Why it's wrong here
CSEK is deprecated and does not integrate well with Dataproc's access control.
- ✗
Enable encryption at rest using Google-managed encryption keys and grant all users the Dataproc Editor role.
Why it's wrong here
Google-managed keys do not allow custom access control; all editors would have access.
- ✓
Use customer-managed encryption keys (CMEK) for the cluster's persistent disks and assign a dedicated service account to the cluster with minimal IAM roles.
Why this is correct
CMEK provides control over keys, and a dedicated service account restricts data access.
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 CSEK (used for Cloud Storage) with CMEK (used for persistent disks), or assume that default encryption combined with VPC Service Controls is sufficient for granular access control to disk data.
Detailed technical explanation
How to think about this question
CMEK for Dataproc persistent disks uses Cloud KMS to wrap the disk encryption keys, allowing the organization to rotate, disable, or audit key usage via Cloud Audit Logs. The dedicated service account must have the `roles/dataproc.worker` and `roles/cloudkms.cryptoKeyEncrypterDecrypter` IAM roles to decrypt the disk keys; without the KMS role, the service account cannot read or write data on the encrypted disks. In a real-world scenario, if the service account is compromised, the organization can revoke access to the CMEK key, effectively locking the data even if the disks are still attached.
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 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
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this PDE question test?
Building and operationalizing data processing systems — This question tests Building and operationalizing data processing systems — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use customer-managed encryption keys (CMEK) for the cluster's persistent disks and assign a dedicated service account to the cluster with minimal IAM roles. — Option D is correct because using customer-managed encryption keys (CMEK) allows the organization to control and manage the encryption keys for persistent disks attached to the Dataproc cluster, ensuring data at rest is encrypted. Assigning a dedicated service account with minimal IAM roles ensures that only that service account can access the data on the cluster disks, following the principle of least privilege.
What should I do if I get this PDE 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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Last reviewed: Jun 24, 2026
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