The answer is that existing objects become inaccessible immediately. This occurs because Cloud Storage relies on the Cloud KMS key to decrypt the object data and metadata on every access request; when the key is disabled, the service loses the cryptographic ability to serve the object, making it unavailable for read, write, or even delete operations until the key is re-enabled. On the Google Professional Cloud Security Engineer exam, this scenario tests your understanding of the tight coupling between Cloud KMS and Cloud Storage CMEK—a common trap is assuming objects remain readable if cached or that only new writes are blocked. Remember the memory tip: "No key, no peek"—without the key, Cloud Storage cannot decrypt a single byte, so access is cut off instantly.
PCSE Ensuring data protection Practice Question
This PCSE practice question tests your understanding of ensuring data protection. 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.
A company uses Cloud Storage with CMEK. The Cloud KMS key is disabled accidentally by an administrator. What will happen to existing objects encrypted with that key?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Objects become inaccessible immediately.
When a Cloud KMS key used for CMEK is disabled, Cloud Storage immediately loses the ability to decrypt the encrypted object data and its associated metadata. Without the key, the service cannot serve the object, making it inaccessible for read, write, or delete operations until the key is re-enabled. This is because CMEK objects are encrypted at rest using the customer-managed key, and Cloud Storage does not maintain a cached copy of the key material.
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.
✗
Objects are automatically re-encrypted with Google-managed keys.
Why it's wrong here
Google does not automatically re-encrypt objects when a CMEK key is disabled.
✓
Objects become inaccessible immediately.
Why this is correct
Disabling the key immediately prevents decryption of any object encrypted with that key.
Related concept
Read the scenario before looking for a memorised answer.
✗
Objects remain accessible until the key is destroyed.
Why it's wrong here
Disabling the key stops its use; only re-enabling restores access.
✗
Objects become inaccessible after a 24-hour grace period.
Why it's wrong here
There is no grace period; disable takes effect immediately.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that disabling a CMEK key has a grace period or that Google will automatically fall back to Google-managed keys, but the correct behavior is immediate inaccessibility with no automatic recovery or re-encryption.
Detailed technical explanation
How to think about this question
Under the hood, Cloud Storage uses envelope encryption: each object is encrypted with a unique data encryption key (DEK), which is then encrypted with the CMEK key (KEK) stored in Cloud KMS. When the CMEK key is disabled, Cloud KMS returns an error for any decrypt operation on the wrapped DEK, causing Cloud Storage to fail all requests for that object. This behavior is consistent with the Cloud KMS key state lifecycle, where 'disabled' immediately prevents cryptographic operations, unlike 'scheduled destruction' which has a delay.
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.
Ensuring data protection — This question tests Ensuring data protection — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Objects become inaccessible immediately. — When a Cloud KMS key used for CMEK is disabled, Cloud Storage immediately loses the ability to decrypt the encrypted object data and its associated metadata. Without the key, the service cannot serve the object, making it inaccessible for read, write, or delete operations until the key is re-enabled. This is because CMEK objects are encrypted at rest using the customer-managed key, and Cloud Storage does not maintain a cached copy of the key material.
What should I do if I get this PCSE 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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Question Discussion
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