DP-420 Study Hub
A study hub for DP-420: Building AI Applications with Azure Cosmos DB, the exam for the Microsoft Certified: Azure Cosmos DB AI Developer Associate certification. It is organized around the three official exam domains, because that is how the exam is scored.
Built from official Microsoft sources. Domains, weightings, and skills come from the Microsoft Learn study guide. Labs come from the official Microsoft Learning courseware repository, and training comes from Microsoft Learn. Every exam simulator question is original and has been fact-checked against current Microsoft Learn documentation.
Microsoft Learn: Study guide for Exam DP-420 · skills measured as of October 6, 2026. Certification page.
A new exam from October 6, 2026
On October 6, 2026, the English version of DP-420 moves to a new outline and a new name, and the certification changes from Azure Cosmos DB Developer Specialty to Azure Cosmos DB AI Developer Associate. This hub covers the new outline. If you sit the exam in another language, or before that date, check the study guide for the skills measured on your exam.
Microsoft Learn Blog: Updates to Azure Cosmos DB and Power Platform developer certifications
The exam#
| Certification | Microsoft Certified: Azure Cosmos DB AI Developer Associate (formerly Azure Cosmos DB Developer Specialty) |
| Level | Intermediate. Role: developer |
| Duration | 100 minutes, proctored through Pearson VUE. The exam may include interactive components |
| Passing score | 700 or greater, on a scale of 1 to 1000 |
| Languages | English, Chinese (Simplified), Chinese (Traditional), French, German, Italian, Japanese, Korean, Portuguese (Brazil), Spanish |
| Retakes | 24 hours after a first failure, then 14 days between attempts, up to 5 attempts in 12 months |
| Renewal | Every 12 months, with a free online assessment on Microsoft Learn |
| Price | Based on the country or region where the exam is proctored |
What Microsoft expects you to know
The audience profile describes a developer who builds cost-effective, high-performance applications on Azure Cosmos DB, using it as the system of record for agent memory, conversation state, retrieval indexes, grounding data, and application data. It asks for experience developing applications in C# or Python, and familiarity with Azure services, generative AI concepts, and retrieval-based systems. Code in this simulator is mostly C# with the .NET SDK, plus Python, the NoSQL query language, JSON policies, and KQL.
Official practice from Microsoft
The free DP-420 practice assessment and the exam sandbox are on Microsoft Learn. Microsoft refreshes practice assessments after an outline update, so for a few weeks after October 6 it can still include topics from the previous outline. Use it alongside the exam simulator here, which follows the new outline.
Watch first: John Savill on Cosmos DB optimization#
John Savill is a colleague here at Microsoft and one of the most generous contributors to the Azure community. His Cosmos DB Optimization deep dive explains the ideas that sit underneath a large share of DP-420: request units, provisioned and autoscale throughput, how physical partitions split, why the partition key matters so much, and how document size, global secondary indexes, and write-heavy or storage-heavy workloads change the design. Watch it before you start the domains, because nearly every performance and cost question comes back to these ideas.
The video guide breaks the video into study sections with the key points of each, mapped to the exam objectives. Every timestamp jumps the player straight to that part.
The three domains#
Weightings are official. Design and develop database solutions is the heaviest domain at 40–45%, and it is where the SDK, data modeling, and partitioning questions live. Domain 3 is new material for anyone who studied the previous outline: AI retrieval, agent memory, and Microsoft Fabric.
Design and develop database solutions
Throughput, consistency, and SDK clients; point reads, queries, patch, batch, bulk, TTL, and optimistic concurrency; data modeling and partition keys; the change feed; and Agent Kit. 48 practice questions.
40–45% Domain 2Secure, optimize, and deploy database solutions
Microsoft Entra authentication and data plane roles, network security and data masking, backup and multi-region configurations, indexing and query tuning, diagnostics, and fleets. 36 practice questions.
30–35% Domain 3Implement AI and analytics capabilities in database solutions
Vector, full text, and hybrid search for AI retrieval and RAG, agent memory stores, and operational analytics with Microsoft Fabric. 28 practice questions.
20–25%Study material#
Exam simulator
112 original, fact-checked questions in every live-exam format: multiple choice and response, drop-down selections in tables and code, drag and drop, build lists, Yes/No grids, scenario series, and two case studies. Exam or practice mode, an optional 100-minute timer, and a PDF of every question.
ReviewCheatsheets
The consistency spectrum, a data modeling and partition key decision flow, the indexing rule matrix, and throughput and partition math.
CodeSDK patterns
Point reads versus queries, optimistic concurrency with ETags, partial document updates, and transactional batch versus bulk, in C# and Python.
Hands-onOfficial labs
All 20 labs from the official DP-420 courseware, most in both C# and Python, grouped by exam domain, plus the local emulator.
WatchVideo guide
John Savill's Cosmos DB optimization deep dive, section by section, with key points, exam objectives, and timestamps that jump the player.
Official and communityResources
The study guide, the certification page, Microsoft Learn training, product documentation by topic, the practice assessment, and the exam sandbox.
Question formats you will see#
The real exam uses several interactive formats. The simulator reproduces each one, so none of them is a surprise on the day.
| Format | What you do |
|---|---|
| Multiple choice | Choose one answer. |
| Multiple response | Choose the stated number of answers (“Choose two”). Each correct selection is worth one point. |
| Drop-down selection | Pick a value from a list in each row of a table, or in each gap of a code segment. |
| Drag and drop | Move answer choices onto the requirement each one satisfies. A choice may be used once, more than once, or not at all. |
| Build list | Move the right actions into the answer area and arrange them in order. |
| Yes or No | Decide whether each statement is true, often about a code segment or a policy. |
| Scenario series | The same scenario repeats with a different proposed solution each time. Decide whether each one meets the goal. You cannot go back to an earlier question in the series. |
| Case study | A company scenario with tabs for its environment and requirements, followed by several questions that refer to it. |
A study plan that works#
- Read the study guide. Focus on the skills measured as of October 6, 2026.
- Watch John Savill’s deep dive to lock in request units, throughput, and partitioning.
- Work through the training listed on the domain pages, one objective at a time.
- Do the labs in the language you know best, and use the free local emulator for extra SDK practice between them.
- Keep the cheatsheets and SDK patterns open while you study. They collect the numbers and method names the exam expects you to recognize.
- Practice one domain at a time in the exam simulator in Practice mode, and read the explanation for every miss.
- Take a full timed run in Exam mode with the 100-minute timer, then the official practice assessment. When you pass both comfortably, book the exam.