Microsoft · DP-420
Microsoft Certified: Azure Cosmos DB Developer Specialty (DP-420) Practice Test
Write efficient queries, create indexing policies, manage, and provision resources in the SQL API and SDK with Microsoft Azure Cosmos DB.
Exam Details
Questions
677
Duration
100 minutes
Passing Score
700/1000
Difficulty
SpecialtyLast Updated
Jan 2025
Topics Covered
Design and implement data modelsDesign and implement data distributionIntegrate an Azure Cosmos DB solutionOptimize an Azure Cosmos DB solutionMaintain an Azure Cosmos DB solution
Microsoft Certified: Azure Cosmos DB Developer Specialty (DP-420) Practice Exam Preparation
Use this DP-420 practice exam to prepare for Microsoft Certified: Azure Cosmos DB Developer Specialty (DP-420) with realistic questions, detailed explanations, and focused study modes. The practice bank includes 677 questions for Microsoft DP-420, so you can review the exam steadily instead of relying on one long cram session.
As you practice, pay extra attention to recurring topics such as Design and implement data models, Design and implement data distribution, Integrate an Azure Cosmos DB solution, Optimize an Azure Cosmos DB solution, and Maintain an Azure Cosmos DB solution. Start with short sessions to identify weak areas, then move into timed quizzes once your accuracy is consistent.
The explanations are especially useful when you want to connect exam wording to the responsibilities and scenarios described in the official certification guidance. Use the free preview first, then unlock the full question bank when you are ready to build a complete study routine.
Exam Domain Breakdown
Design and implement data models38%
Design and implement data distribution8%
Integrate an Azure Cosmos DB solution8%
Optimize an Azure Cosmos DB solution18%
Maintain an Azure Cosmos DB solution28%
Exam Overview
The Microsoft Certified: Azure Cosmos DB Developer Specialty (DP-420) validates subject matter expertise in designing, implementing, and monitoring cloud-native applications that store and manage data using Azure Cosmos DB. The certification covers the full development lifecycle: modeling non-relational data, selecting partition keys, managing throughput and scaling, implementing the SQL API and .NET/Java SDKs, writing server-side JavaScript (stored procedures, triggers, user-defined functions), and integrating Cosmos DB with other Azure services such as Azure Functions, Azure Synapse Link, and Event Hubs.
The exam was last updated on January 27, 2025, and reflects current platform capabilities including hierarchical partition keys, the integrated cache, Always Encrypted, and Azure Synapse Link with Change Data Capture. Candidates are assessed on their ability to optimize query performance through indexing strategies and cost analysis, implement change feeds, configure backup and restore, enforce security controls using Microsoft Entra ID and Azure RBAC, and automate operations using Azure Resource Manager templates and PowerShell/CLI.
Who Should Take This Exam
This certification is intended for developers and data engineers with hands-on experience building Azure applications that rely on Azure Cosmos DB for NoSQL as their primary data store. Suitable job titles include Azure Developer, Cloud Application Developer, and Data Engineer. Candidates typically have two or more years of experience working with Azure services and are comfortable reading C# or Java application code, writing SQL queries for the Cosmos DB NoSQL API, and interpreting JSON documents.
Professionals pursuing this certification often work in roles where they are responsible for both the data modeling decisions and the operational health of a Cosmos DB solution—including security, availability, resilience, and performance. It is particularly relevant for those building globally distributed, high-throughput applications such as IoT platforms, e-commerce systems, and real-time analytics pipelines.
Prerequisites
Microsoft does not enforce formal prerequisites for DP-420, but candidates are expected to have practical experience developing applications for Azure and working with Azure Cosmos DB database technologies. Specifically, candidates should be proficient with the Azure Cosmos DB for NoSQL API, able to write efficient SQL queries against it, create and tune indexing policies, and use the Azure Cosmos DB SDK (C# or Java). Familiarity with JSON structure and the ability to write server-side JavaScript for stored procedures and triggers is also required.
A solid understanding of Azure fundamentals—including resource provisioning, Azure role-based access control (RBAC), Azure Monitor, and ARM templates—is strongly recommended. Candidates who have completed the AZ-900 (Azure Fundamentals) or AZ-204 (Azure Developer Associate) certification will find much of this background knowledge directly applicable. Microsoft's free learning path DP-420T00 (Design and Implement Cloud-Native Applications with Azure Cosmos DB) is the official preparatory course.
Exam Format
Exam DP-420 is a proctored assessment delivered through Pearson VUE, available both online (remote proctored) and at Pearson VUE test centers. Candidates are given 100 minutes to complete the exam. The number of questions is not publicly disclosed and may vary, but the exam may include multiple question types such as multiple choice, drag-and-drop, build-list, case studies, and interactive lab components. A score of 700 or higher on a scale of 100–1000 is required to pass.
The exam is available in English, Japanese, Chinese (Simplified), Chinese (Traditional), Korean, German, French, Spanish, Portuguese (Brazil), and Italian. If taking the exam in a non-English localization, candidates may request an additional 30 minutes. The certification expires annually and can be renewed at no cost by passing a free online assessment on Microsoft Learn. The exam price is approximately $165 USD, varying by country or region of the testing location.
Skills Measured
- 1.Design and implement data models (35–40%): Covers non-relational data modeling for the NoSQL API including multi-entity containers, document denormalization, reference patterns, TTL configuration, document versioning, and schema versioning. Also includes partitioning strategy selection, synthetic and hierarchical partition keys, throughput sizing (serverless vs. provisioned), SDK client connectivity (gateway vs. direct mode), SQL query implementation (arrays, aggregation, subqueries, functions), SDK CRUD and patch operations, transactional batch, optimistic concurrency with ETags, session consistency, pagination, and server-side JavaScript (stored procedures, triggers, UDFs).
- 2.Design and implement data distribution (5–10%): Covers global replication strategy including automatic and manual failover policies, consistency model selection (strong, bounded staleness, session, consistent prefix, eventual) and their trade-offs in latency, availability, and RU cost. Also includes multi-region write configuration and custom conflict resolution policies for the NoSQL API.
- 3.Integrate an Azure Cosmos DB solution (5–10%): Covers enabling and querying Azure Synapse Link for analytical workloads, choosing between Synapse Link and the Spark Connector, implementing custom partitioning in Synapse Link, Change Data Capture in the analytical store, and time travel. Also includes integration patterns using Azure Functions with Change Feed for denormalization, referential integrity, aggregation, and archiving, as well as Azure AI Search integration and Event Hubs eventing.
- 4.Optimize an Azure Cosmos DB solution (15–20%): Covers query performance tuning through index adjustments, RU cost calculation for queries and point operations, use of the Azure Cosmos DB integrated cache, change feed processing via Azure Functions triggers and SDK consumers, change feed estimator for scaling, and defining indexing strategies (read-heavy vs. write-heavy, composite indexes, custom indexing policies).
- 5.Maintain an Azure Cosmos DB solution (25–30%): Covers monitoring with Azure Monitor (normalized RU usage, server-side latency, partition distribution, replication metrics), configuring alerts and diagnostic logs, implementing periodic and continuous backup, point-in-time recovery, and security controls including network access, encryption (service-managed and customer-managed keys, Always Encrypted), Microsoft Entra ID data plane access, Azure RBAC for control plane, CORS, Key Vault key management. Also includes data movement strategies (SDK bulk, Azure Data Factory, Kafka connector, Stream Analytics, Spark Connector, IoT Hub) and DevOps automation with ARM templates and PowerShell/CLI.
Study Tips
- Use the official Microsoft Learn learning path DP-420T00 (Design and Implement Cloud-Native Applications with Azure Cosmos DB) as your primary study resource—it maps directly to exam domains and includes hands-on sandbox exercises for SDK operations, indexing, and partitioning.
- Take the free official Practice Assessment on Microsoft Learn (Assessment ID 104) multiple times. It mirrors the style and difficulty of real exam questions and provides explanations that link back to documentation—use it to identify weak domains before exam day.
- Set up a free-tier Azure Cosmos DB account and the Azure Cosmos DB Emulator for offline development. Practice writing NoSQL API queries, configuring composite indexes via the Data Explorer, implementing stored procedures in JavaScript, and using the .NET or Java SDK to perform batch and patch operations.
- Focus significant study time on partitioning and indexing—together these two sub-domains underpin both the Design and implement data models domain (35–40%) and the Optimize domain (15–20%). Work through partition key selection scenarios, calculate RU costs for cross-partition queries, and experiment with custom indexing policies to understand read/write trade-offs.
- Study consistency models in depth: understand the five levels (strong, bounded staleness, session, consistent prefix, eventual), their RU cost implications, latency characteristics, and when to override the account-level consistency at the per-request level using SDK request options.
- Review the Maintain domain (25–30%) carefully—it is the second-largest domain. Practice configuring Azure Monitor diagnostic settings, setting up alerts for 429 (rate-limited) requests, and walking through both periodic and continuous backup/restore workflows in the Azure portal.
- Consult the official DP-420 Study Guide on Microsoft Learn (aka.ms/dp420-StudyGuide) to review the full list of objectives as of January 27, 2025. Pay particular attention to recently added topics such as Always Encrypted, hierarchical partition keys, and Synapse Link Change Data Capture, which reflect the latest exam update.
Career Benefits
Earning the Azure Cosmos DB Developer Specialty positions professionals for roles such as Senior Azure Developer, Cloud-Native Application Architect, and Data Platform Engineer—positions that command premium salaries due to the specialized nature of globally distributed database design. According to industry surveys, Azure-certified developers with specialty credentials typically earn between $120,000 and $165,000 USD annually in North American markets, with variation by region and total experience. Demand for Cosmos DB expertise is driven by enterprises building IoT, gaming, retail, and financial services applications that require low-latency, multi-region access at scale.
Compared to the broader AZ-204 (Azure Developer Associate), DP-420 demonstrates deep, focused expertise in a specific high-value technology—making it particularly compelling on a resume for organizations heavily invested in the Azure data platform. The certification is recognized globally and renewable annually at no cost, ensuring that credential holders remain current with platform evolution. It also pairs well with certifications such as DP-203 (Azure Data Engineer Associate) for professionals who straddle application development and data engineering responsibilities.
Sample Questions
5 sample questions with answers and explanations. Start a practice session to test yourself across all 677 questions.
Preview — answers shown1. At ProcessFlow Industries, the team has created an IndexingPolicy object and wants to add it to their container configuration. They need to create a container with a custom indexing policy. Which class should they use to combine the container properties with the indexing policy?
AContainerProperties class to configure container settings including indexing policy
BIndexedContainer class for containers with custom indexing
CContainerOptions class to specify container creation options
DContainerConfiguration class for comprehensive container setup
Explanation
The ContainerProperties class is used to configure container settings including the indexing policy. You set properties like Id (container name), PartitionKeyPath, and IndexingPolicy, then pass the ContainerProperties object to CreateContainerIfNotExistsAsync to create a container with the custom indexing configuration.
2. StreamProcessor Inc has an Azure Cosmos DB for NoSQL account and develops a change feed processor using C# code. They need to create an on-demand change feed estimator. The code shows: ChangeFeedEstimator changeFeedEstimator = monitoredContainer.GetChangeFeedEstimator(changeFeedEstimator, TARGET). What should replace the TARGET placeholder?
AA callback function for estimate handling
BThe processor instance name string
CA TimeSpan value for polling interval
DThe leaseContainer object reference
Explanation
The TARGET placeholder should be replaced with the leaseContainer object reference. The change feed estimator requires access to the same lease container used by the change feed processor to calculate accurate lag estimates. The lease container contains the checkpoint information that allows the estimator to determine how far behind the processor is in reading changes. A TimeSpan value would be used for polling intervals in different contexts but not as a constructor parameter for the estimator. Callback functions are used in push-model scenarios, not for on-demand estimators. The processor instance name is specified when creating processors, not estimators. The lease container reference provides the necessary checkpoint data for lag estimation calculations.
3. TechAdvantage Solutions is optimizing their indexing policy and encounters a scenario where they have conflicting included and excluded paths. They include /product/specifications/* and exclude /product/specifications/weight/?. How does Azure Cosmos DB resolve this conflict?
AThe included path takes precedence and all specifications are indexed
BThe conflict causes container creation to fail with an error
CThe excluded path takes precedence because /weight/? is more specific than /*
DBoth paths are ignored due to the conflict and default indexing is used
Explanation
Azure Cosmos DB resolves path conflicts by giving precedence to the more specific path. The excluded path /product/specifications/weight/? is more specific than the included path /product/specifications/*, so the weight property will be excluded from indexing while all other properties under specifications are indexed. Specificity determines precedence in conflict resolution.
4. Your application at CloudNative Dynamics successfully executes a transactional batch with two create operations. The team needs to extract the first created item from the batch response. Which method should they use to access the individual operation results?
Aresponse.GetOperationResultAtIndex<Product>(0) to get the first result
Bresponse.Results[0].GetResource<Product>() to extract the first item
Cresponse.GetItemAtIndex<Product>(0) to access the first created item
Dresponse.GetResult<Product>(0) to retrieve the first operation outcome
Explanation
The GetOperationResultAtIndex<Product>(index) method is used to retrieve individual operation results from a transactional batch response. The index parameter (0-based) specifies which operation result to retrieve. This method returns a TransactionalBatchOperationResult<Product> that contains the Resource property with the actual item.
5. MultiRegionApp Corp operates a content delivery system across North America, Europe, and Asia regions with Azure Cosmos DB multi-region writes enabled. They experience a complete regional outage in their primary write region and need to maintain service availability. How should they handle this multi-region write scenario during the outage?
AMaintain multi-region writes and allow the system to automatically handle write distribution across remaining healthy regions
BDisable multi-region writes temporarily and promote a single region to handle all write operations during the outage
CConfigure write region priorities to ensure writes automatically failover to the next available region in priority order
DImplement application-level write redirection to manually route all writes to a specific healthy region
Explanation
Multi-region writes are specifically designed to handle regional outages by automatically distributing writes across healthy regions without manual intervention. This provides the highest availability and requires no administrative action during outages. Disabling multi-region writes during outages eliminates the availability benefits and adds operational complexity. Application-level redirection adds unnecessary complexity when the multi-region write feature handles this automatically. Write region priorities are not applicable to multi-region write scenarios - they apply to single-write-region configurations with automatic failover.
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