Free Exam DP-420: Building AI Applications with Azure Cosmos DB Practice Questions

Sample Practice Questions

Try these 10 sample questions from the Exam DP-420: Building AI Applications with Azure Cosmos DB practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1A read must always return the most recently committed version of an item. Which Azure Cosmos DB consistency level provides this guarantee?

   1. A. Session
   2. B. Strong
   3. C. Bounded staleness
   4. D. Eventual

   Answer: B

   Explanation: The documentation states, "The reads are guaranteed to return the most recent committed version of an item." This is the strong consistency guarantee; session is scoped to a session, bounded staleness permits lag, and eventual permits stale reads.

   Reference: Consistency levels in Azure Cosmos DB — Strong consistency

2. 2An Azure-hosted application must authenticate to Cosmos DB while eliminating application-managed credentials and their rotation. Which identity mechanism meets this objective?

   1. A. A service principal using an application-managed client secret
   2. B. A service principal using an application-managed certificate
   3. C. A managed identity in Microsoft Entra ID
   4. D. An account key retrieved by the application from Key Vault

   Answer: C

   Explanation: Microsoft states, "Managed identities eliminate the need to manage credentials by providing an automatically managed identity in Microsoft Entra ID." Account keys and connection strings remain credentials that the application must protect.

   Reference: Secure your Azure Cosmos DB for NoSQL account — Identity management, managed identities

3. 3A vector policy declares 1,536 dimensions for /embedding. What requirement applies to vectors stored at that path?

   1. A. 1,536 is a minimum; vectors can have different larger lengths
   2. B. 1,536 is a maximum; vectors can have different smaller lengths
   3. C. All vectors at the path should have the declared dimensionality
   4. D. 1,536 constrains query vectors, but stored vectors can vary in length

   Answer: C

   Explanation: Microsoft states, "All vectors in a path should have the same number of dimensions." A policy describes the common vector shape for that path, rather than allowing per-item dimensionality changes.

   Reference: Vector search in Azure Cosmos DB for NoSQL — Container vector policies, dimensions

4. 4A globally distributed, single-write-region account uses bounded staleness with a version-count limit K and a time limit T. How do these configured limits constrain replication lag?

   1. A. The version-count limit governs writes, while the time limit governs reads
   2. B. Replication lag may continue until both configured limits have been reached
   3. C. Only one limit is active, selected when the account is configured
   4. D. The first of the two configured limits reached bounds the permitted lag

   Answer: D

   Explanation: Microsoft describes "The number of versions (K) of the item" and "The time interval (T) reads might lag behind the writes" as the two bounded-staleness limits. The first limit reached controls the permitted lag; the other choices do not provide these configured bounds.

   Reference: Consistency levels in Azure Cosmos DB — Bounded staleness consistency

5. 5An application's identity needs permission to query and create items, without administrative account management. Which authorization plane governs those data operations?

   1. A. Native data-plane RBAC with appropriate container-scoped data actions
   2. B. The Azure Cosmos DB Account Reader control-plane role alone
   3. C. The Cosmos DB Operator control-plane role alone
   4. D. The Azure Contributor control-plane role alone

   Answer: A

   Explanation: Microsoft instructs, "Use native data plane role-based access control to query, create, and access items within a container". Administrative roles and network access alone do not grant those item permissions.

   Reference: Secure your Azure Cosmos DB for NoSQL account — Identity management, data plane authorization

6. 6A vector workload considers changing stored vector elements from float32 to float16. What documented tradeoff should be evaluated?

   1. A. About half the vector storage footprint, with possible accuracy reduction
   2. B. About half the vector storage footprint, with no possible accuracy reduction
   3. C. About one quarter of the vector storage footprint, with possible accuracy reduction
   4. D. About twice the vector storage footprint, with improved numeric precision

   Answer: A

   Explanation: Microsoft states, "Using float16 instead can reduce the storage footprint of vectors by 50%, however some reduction in accuracy may result." Storage savings do not imply a guarantee of unchanged accuracy.

   Reference: Vector search in Azure Cosmos DB for NoSQL — Container vector policies, float16 Note

7. 7Which consistency level explicitly provides read-your-writes within a single client session without requiring strong consistency?

   1. A. Session
   2. B. Eventual
   3. C. Consistent prefix
   4. D. Bounded staleness

   Answer: A

   Explanation: Microsoft states, "In session consistency, within a single client session, reads are guaranteed to honor the read-your-writes, and write-follows-reads guarantees." This is a session-scoped guarantee, unlike the lag bound or weaker guarantees of the alternatives.

   Reference: Consistency levels in Azure Cosmos DB — Session consistency

8. 8A policy requires all application authentication to use Microsoft Entra ID rather than account keys. Which account configuration enforces this authentication boundary?

   1. A. Set properties.disableLocalAuth to false
   2. B. Rotate both account keys but leave local authentication enabled
   3. C. Assign data-plane roles but leave local authentication enabled
   4. D. Set properties.disableLocalAuth to true

   Answer: D

   Explanation: Microsoft's disable-key-authentication procedure sets "--set properties.disableLocalAuth=true". Assigning roles or rotating keys alone leaves key-based authentication available unless local authentication is disabled.

   Reference: Connect to Azure Cosmos DB for NoSQL using role-based access control and Microsoft Entra ID — Disable key-based authentication

9. 9What is the documented maximum vector dimensionality for the flat index type?

   1. A. 256 dimensions
   2. B. 1,536 dimensions
   3. C. 4,096 dimensions
   4. D. 505 dimensions

   Answer: D

   Explanation: Microsoft states, "there's a limitation of 505 dimensions for vectors on a flat index." The 4,096 limit applies to other listed vector index types, not flat.

   Reference: Vector search in Azure Cosmos DB for NoSQL — Vector indexing policies, flat index considerations

10. 10A service passes a session token to another SDK client. What does that token represent when the receiving client reads?

    1. A. An exact historical item version
    2. B. A maximum version the client may read
    3. C. A minimum version barrier for the read
    4. D. An account-wide lock on subsequent writes

    Answer: C

    Explanation: The documentation explains, "The Session Token is used as a minimum version barrier but not as a specific (possibly historical) version of the data to be retrieved from the database." It is neither a snapshot selector, upper bound, nor write lock.

    Reference: Consistency levels in Azure Cosmos DB — Session consistency, session token semantics