The answer is that the CMEK key was disabled by the key administrator for security reasons. This is correct because Cloud SQL for MySQL relies on the customer-managed encryption key to be in an enabled state to encrypt and decrypt data at rest; when the key is disabled, the instance loses the ability to access its own encrypted data, rendering it inaccessible with the exact error described. On the Google Professional Cloud Database Engineer exam, this scenario tests your understanding of CMEK lifecycle management and the critical dependency between Cloud SQL and Cloud KMS—a common trap is assuming the issue is a permission or network problem, when the root cause is simply the key’s state. To remember this, think of the CMEK key as a light switch: if an administrator flips it off (disables it), the entire database goes dark and cannot function until the switch is turned back on.
PCDE Plan and manage database infrastructure Practice Question
This PCDE practice question tests your understanding of plan and manage database infrastructure. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 has a Cloud SQL for MySQL instance that stores sensitive data. They need to encrypt the data at rest using a customer-managed encryption key (CMEK). The database engineer creates a Cloud KMS key ring and key, and configures the Cloud SQL instance to use CMEK. However, after 30 days, the instance becomes inaccessible and the error message indicates the CMEK key is disabled. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The CMEK key was disabled by the key administrator for security reasons.
Option A is correct because the error message indicates the CMEK key is disabled, and the most common cause in a controlled environment is that the key administrator intentionally disabled the key. Cloud SQL for MySQL requires the CMEK key to be enabled to encrypt and decrypt data at rest; if the key is disabled, the instance cannot access its data and becomes inaccessible. This aligns with the scenario where no other configuration changes are mentioned, making administrative action the likely cause.
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.
✓
The CMEK key was disabled by the key administrator for security reasons.
Why this is correct
If the key is disabled, Cloud SQL cannot access it, causing the instance to become unavailable.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Cloud SQL instance exceeded the number of times it can access the CMEK key.
Why it's wrong here
There is no access count limit for CMEK keys.
✗
The CMEK key was rotated, and the old key version was disabled.
Why it's wrong here
Key rotation creates a new version; the old version remains enabled for decryption unless disabled.
✗
The CMEK key expired, causing automatic disablement.
Why it's wrong here
Cloud KMS keys do not auto-expire; they must be explicitly disabled or deleted.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse key rotation with key disablement, assuming that rotating a key automatically disables the old version, but in Cloud KMS, old key versions remain enabled unless explicitly disabled.
Detailed technical explanation
How to think about this question
Cloud KMS CMEK keys are symmetric encryption keys used by Cloud SQL to encrypt data at rest via envelope encryption. When a key is disabled, Cloud SQL cannot decrypt the data encryption keys (DEKs) stored with the data, causing the instance to fail to start or become inaccessible. In practice, key administrators often disable keys during security incidents or audits, but this can lead to production outages if not coordinated with database teams.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Plan and manage database infrastructure — This question tests Plan and manage database infrastructure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The CMEK key was disabled by the key administrator for security reasons. — Option A is correct because the error message indicates the CMEK key is disabled, and the most common cause in a controlled environment is that the key administrator intentionally disabled the key. Cloud SQL for MySQL requires the CMEK key to be enabled to encrypt and decrypt data at rest; if the key is disabled, the instance cannot access its data and becomes inaccessible. This aligns with the scenario where no other configuration changes are mentioned, making administrative action the likely cause.
What should I do if I get this PCDE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 PCDE 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 PCDE 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.