Google ACE Configuring Access and Security Practice Question
A company has a Cloud SQL instance with CMEK enabled. The Cloud KMS key used for encryption is accidentally disabled. What is the impact on the Cloud SQL instance?
⚠ Common exam trap
ACE often tests the misconception that a disabled CMEK key only affects new data encryption, when in fact it renders the entire instance unavailable because existing data cannot be decrypted.
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
✓
The instance becomes unavailable and cannot be started until the key is re-enabled.
When a Cloud KMS key used for CMEK is disabled, the Cloud SQL instance cannot access the key to decrypt its data. As a result, the instance becomes unavailable and cannot be started until the key is re-enabled. This is because the instance requires the key for both read and write operations.
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 instance will be automatically deleted after 30 days.
Why it's wrong here
Disabling a CMEK key for a Cloud SQL instance does not invoke any lifecycle policy that deletes the instance. Cloud SQL instances remain in place when their encryption key is disabled; they simply enter an unusable state. The 30-day delay you may recall applies to Cloud KMS key destruction, where a key scheduled for destruction is held for 30 days before permanent deletion—this is not tied to instance deletion.
- ✓
The instance becomes unavailable and cannot be started until the key is re-enabled.
Why this is correct
Cloud SQL with CMEK uses the customer-managed key for every data-plane operation, including reads and writes to the database, logs, and system tables. When the key is disabled, the instance loses access to the key material, causing the database engine to fail all I/O requests immediately. Consequently, the instance becomes unavailable and cannot be started or used until the key is re-enabled in Cloud KMS; re-enabling the key automatically restores normal operation without manual intervention.
- ✗
A read replica can be promoted to replace the primary.
Why it's wrong here
A read replica in Cloud SQL shares the same CMEK configuration as its primary instance, including the same key version. If the key is disabled, the replica cannot decrypt its data and becomes as unavailable as the primary, so it cannot serve read traffic. Promotion to a primary requires a functioning replica with access to its data store; because the replica is equally blocked by the disabled key, this option is not a viable failover path.
- ✗
The instance continues to operate normally, but new data cannot be encrypted.
Why it's wrong here
Cloud SQL does not operate in a degraded mode when the CMEK key is disabled; it requires the key for both encrypted reads and writes, not just for new data. The instance must decrypt the database pages, transaction logs, and system catalogs before it can process any request, including a simple login. As a result, the instance halts entirely rather than continuing to serve existing data, and new data cannot be written because the whole instance is non-functional, not just encryption of new rows.
Go deeper
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Key term
Cloud SQL
Cloud SQL is a fully managed relational database service that lets you set up, maintain, and scale SQL databases (like MySQL, PostgreSQL, and SQL Server) in the cloud without managing the underlying infrastructure.
Key term
Cloud KMS
Cloud KMS (Key Management Service) is a cloud-based service that lets you create, manage, and use encryption keys to protect your data at rest and in transit.
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Google Cloud exam blueprint
This ACE 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 ACE exam.