The answer is to change the Cosmos DB account's default identity to a user-assigned managed identity and then remove that identity's access to the Key Vault. This works because Cosmos DB caches the customer-managed key for up to an hour, so simply disabling the key version in Key Vault does not immediately revoke access; by revoking the managed identity’s permission to unwrap the key, you force the database to lose its ability to decrypt the data at rest, making it inaccessible instantly. On the AZ-500 exam, this scenario tests your understanding of the difference between key lifecycle actions (disable, delete, rotate) and access control—a common trap is assuming disabling the key version suffices, but the exam emphasizes that Cosmos DB’s key caching delays revocation. To remember: think “cut the identity, not the key”—revoking the managed identity’s access to Key Vault is the only way to immediately revoke CMK access for Cosmos DB.
AZ-500 Secure compute, storage, and databases Practice Question
This AZ-500 practice question tests your understanding of secure compute, storage, and databases. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
Your organization has an Azure Cosmos DB account that stores IoT telemetry data. The data is ingested from multiple devices and is time-sensitive. Security requirements mandate that all data be encrypted at rest using customer-managed keys (CMK) stored in Azure Key Vault. You configure CMK for the Cosmos DB account. After a security incident, you need to revoke access to the data immediately by disabling the CMK in Key Vault. However, you find that data can still be read from Cosmos DB. You need to ensure that disabling the key renders the data inaccessible. What should you do?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "immediately / without restart"
Why it matters: Time or reboot constraint — the correct answer must take effect right away without requiring a reboot or reload.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change the Cosmos DB account's default identity to a user-assigned managed identity and remove that identity's access to the Key Vault.
Option C is correct: Changing the default identity to a user-assigned managed identity and revoking its access to the Key Vault will disable the CMK and make the data inaccessible. Option A: Disabling the key version does not immediately revoke access; Cosmos DB caches the key. Option B: Deleting the key may be irreversible and does not guarantee immediate revocation. Option D: Rotating the key does not revoke the old key; data encrypted with the old key remains accessible.
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.
✗
Rotate the CMK to a new key version and update the Cosmos DB account to use the new key.
Why it's wrong here
Rotation does not revoke the old key; data encrypted with old key remains accessible.
✗
Delete the CMK from Key Vault.
Why it's wrong here
Deleting the key is permanent and may not immediately revoke access due to caching.
✗
Disable the specific key version used by Cosmos DB in Key Vault.
Why it's wrong here
Cosmos DB caches the key; disabling the version may not take effect immediately.
✓
Change the Cosmos DB account's default identity to a user-assigned managed identity and remove that identity's access to the Key Vault.
Why this is correct
This revokes access to the key, causing Cosmos DB to lose ability to decrypt.
Clue confirmation
The clue word "immediately / without restart" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-500 question in full detail.
Identify which AZ-500 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Secure compute, storage, and databases — This question tests Secure compute, storage, and databases — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Change the Cosmos DB account's default identity to a user-assigned managed identity and remove that identity's access to the Key Vault. — Option C is correct: Changing the default identity to a user-assigned managed identity and revoking its access to the Key Vault will disable the CMK and make the data inaccessible. Option A: Disabling the key version does not immediately revoke access; Cosmos DB caches the key. Option B: Deleting the key may be irreversible and does not guarantee immediate revocation. Option D: Rotating the key does not revoke the old key; data encrypted with the old key remains accessible.
What should I do if I get this AZ-500 question wrong?
Identify which AZ-500 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "immediately / without restart". Time or reboot constraint — the correct answer must take effect right away without requiring a reboot or reload.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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