The answer is that key version 1 was deleted after the new primary was created. This is correct because Cloud KMS key version deletion is irreversible; once a key version is destroyed, any data encrypted with that specific version becomes permanently undecryptable. In this scenario, the security team promoted version 2 as the primary, but then manually deleted version 1, which was used to encrypt backups before May 1, 2023. On the Google Professional Cloud Security Engineer exam, this tests your understanding that key rotation does not automatically delete old versions—deletion is a separate, destructive action. A common trap is confusing disabling a key version with deleting it; disabling only prevents new encryption but allows decryption of existing data. Remember the memory tip: “Delete destroys, disable delays.”
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.
Network Topology
Refer to the exhibit. The security team created this key for encrypting database backups. After an audit, they found that data encrypted before May 1, 2023, cannot be decrypted. 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
✓
Key version 1 was deleted after the new primary was created.
Option B is correct because when a new primary key version is created in Cloud KMS, the old primary key version is not automatically deleted. However, if the old key version (version 1) was manually deleted after promoting version 2 as the primary, any data encrypted with version 1 becomes permanently undecryptable. The audit finding that data encrypted before May 1, 2023 cannot be decrypted directly indicates that the key version used for that encryption (likely version 1) is no longer available, not just disabled or rotated.
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 rotation period is too short, causing old versions to be destroyed.
Why it's wrong here
Rotation period 7776000s (90 days) does not cause deletion.
✓
Key version 1 was deleted after the new primary was created.
Why this is correct
If version 1 was deleted, data encrypted with it cannot be decrypted.
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 primary key version is disabled.
Why it's wrong here
The primary key state is ENABLED.
✗
The algorithm GOOGLE_SYMMETRIC_ENCRYPTION is not supported by HSM.
Why it's wrong here
HSM supports symmetric encryption.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the distinction between key rotation (which creates new versions) and key version deletion (which removes the ability to decrypt old data), leading candidates to incorrectly assume that rotation alone causes decryption failures.
Detailed technical explanation
How to think about this question
In Google Cloud KMS, each key version has a unique key material and state (enabled, disabled, destroyed, or scheduled for destruction). When a key version is destroyed, the key material is permanently deleted and cannot be recovered, making any ciphertext encrypted with that version undecryptable. The rotation period only controls when a new version is automatically created; it does not delete old versions unless a separate lifecycle policy or manual action is taken. This is a common misconfiguration where teams rotate keys but forget to retain old versions for legacy data decryption.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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: Key version 1 was deleted after the new primary was created. — Option B is correct because when a new primary key version is created in Cloud KMS, the old primary key version is not automatically deleted. However, if the old key version (version 1) was manually deleted after promoting version 2 as the primary, any data encrypted with version 1 becomes permanently undecryptable. The audit finding that data encrypted before May 1, 2023 cannot be decrypted directly indicates that the key version used for that encryption (likely version 1) is no longer available, not just disabled or rotated.
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.
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.
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Question Discussion
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