Microsoft · DP-420
Microsoft Certified: Azure Cosmos DB Developer Specialty (DP-420) Practice Tests
Write efficient queries, create indexing policies, manage, and provision resources in the SQL API and SDK with Microsoft Azure Cosmos DB.
Exam Details
Practice Questions
677
≈ 13 practice exams
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. The full bank has 677 questions, enough for 13 full-length practice exams.
Preview — answers shown1. UrbanRetail Corp is developing an order management system using Azure Cosmos DB for NoSQL. They expect approximately 15 GB of data per customer per city. Most queries will filter by customerId, with fewer queries filtering by both customerId and cityId. What partition key format should they recommend?
AUse cityId as the single partition key
BUse customerId as the single partition key
CUse a synthetic key combining timestamp and customer information
DCreate a hierarchical partition key with customerId first, then cityId
Explanation
A hierarchical partition key with customerId as the primary level and cityId as secondary provides the best solution for this scenario. This structure supports queries filtering by customerId alone (the most common pattern) while also enabling efficient queries by both customerId and cityId. The hierarchical approach allows each customer-city combination to store up to 20 GB, accommodating the expected 15 GB per customer per city. Using only customerId could hit the 20 GB logical partition limit and wouldn't support city-based filtering efficiently. Using only cityId doesn't support the primary query pattern of filtering by customer. A synthetic key adds complexity without addressing the specific data size and query pattern requirements.
2. ModernData Corp is evaluating database technologies for their new application and wants to understand current trends in database technology. They need to make informed decisions about which technologies align with their long-term strategy. What are the key trends shaping modern database technology?
AModern database trends focus exclusively on returning to traditional relational databases and abandoning all NoSQL innovations
BKey trends include multi-model databases, cloud-native architectures, serverless computing, AI integration, and hybrid transactional-analytical processing
CModern database trends are purely marketing concepts with no real technical innovations or practical benefits
DThe only important trend in database technology is increasing storage capacity without regard for other capabilities
Explanation
Modern database technology trends include multi-model databases that support different data models in single systems, cloud-native architectures designed for cloud infrastructure, serverless computing that eliminates infrastructure management, AI integration for automated optimization and insights, and hybrid systems that combine transactional and analytical capabilities (HTAP). The industry isn't abandoning NoSQL - instead, it's integrating the best features from different database approaches. Storage capacity is important but modern trends focus on intelligent data processing, automated management, and unified platforms that serve multiple use cases. These trends represent real technical innovations addressing evolving business requirements for more flexible, scalable, and intelligent data management solutions.
3. 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.
4. ProcessOptimal Industries has an Azure Cognitive Search solution that needs to handle both incremental updates and full re-indexing scenarios. They want to understand when full re-indexing is necessary versus incremental updates. Which scenario requires a full re-indexing operation?
AWhen updating existing items in the source container
BWhen adding new items to the source container
CWhen the indexer schedule frequency is changed
DWhen modifying the search index schema or field configurations
Explanation
Full re-indexing is required when the search index schema changes, such as adding new fields, changing field properties (searchable, filterable, etc.), or modifying analyzers. These structural changes require reprocessing all data to populate the new schema properly. Incremental updates handle new or modified items, but schema changes need complete index rebuilds.
5. DataPipelineConfig Corp needs to configure Azure Data Factory to read data from their Azure Cosmos DB for NoSQL container. They want to filter the data during the read operation to reduce the amount of data transferred and processed. The container has products with various price ranges, and they only need products priced above 500. How should they configure the source component?
AConfigure the source to read all data and apply filters in subsequent transformation activities
BConfigure the source to use change feed filtering to capture only price changes above 500
CSet up partition-based filtering to read only from specific logical partitions containing high-priced products
DUse a SQL query in the source configuration to filter data at the database level: SELECT id, categoryId, price, quantity, name FROM products WHERE price > 500
Explanation
Azure Data Factory allows SQL queries in the source configuration to filter data at the database level, reducing data transfer and processing overhead. The content shows an example query 'SELECT id, categoryId, price, quantity, name FROM products WHERE price > 500' for exactly this scenario. This approach is more efficient than reading all data and filtering later. Partition-based filtering requires knowing which partitions contain the desired data and doesn't provide the same flexibility as SQL filtering. Change feed filtering is for capturing data changes, not for filtering existing data during batch reads.
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