DP-420 Azure Cosmos DB Developer Specialty Practice Exams

Pass the DP-420 exam on your first attempt.

This is a specialty certification, and it behaves like one. There is no broad survey of Azure services to pad your score — every question is about designing and running applications on a globally distributed NoSQL database, and the exam assumes you have actually done it. That narrowness is the point. Very few developers can defend a partitioning decision under cost and latency constraints, and this credential exists to identify the ones who can.

The exam was also updated recently, and the shift was toward applied judgement. You are given a workload with constraints attached and asked which partition key, indexing policy, consistency level or throughput model fits it. Memorising service limits will not get you there, because most of the wrong answers are configurations that work perfectly well until the data grows, the traffic skews, or the bill arrives.

What you get

• Full-length practice tests that mirror the structure, difficulty and pacing of the live exam

• A detailed explanation on every single question — every option addressed individually, because on this exam the wrong answers are usually valid configurations that fail on scale, cost or latency

• Coverage across the full skills outline: designing and implementing data models, designing and implementing data distribution, integrating with the wider Azure platform, optimizing solutions, and maintaining them in production

• Deep partitioning coverage, the area that decides more DP-420 outcomes than any other — choosing partition keys, handling skew, synthetic keys, hierarchical strategies and what happens when you get it wrong

• Request unit and cost questions throughout, since cost control is now central rather than incidental

• Query and indexing depth: query execution, indexing policies, composite indexes, and diagnosing an expensive query from its metrics

• Code-based questions using the SDK patterns the exam expects, alongside configuration and architecture scenarios

• Kept current with the published skills outline

• Unlimited retakes, randomized question order, mobile-friendly, lifetime access

How to use this course

Sit the first test cold to establish a baseline. Read every explanation, including on correct answers, because the same handful of decisions — partition key, consistency level, throughput model, index policy — recur across scenarios with different correct choices, and the reasoning is what transfers. Then go and build. Create a container, load enough data to see a hot partition form, watch the request unit charge change when you alter the indexing policy, and run a cross-partition query badly on purpose. The metrics blade teaches this material faster than any explanation can.

Worth knowing: Microsoft recommends solid Azure development experience before attempting this exam, and most candidates find a year or more working with the database itself makes the difference. Specialty certifications also carry renewal requirements, and Microsoft has been consolidating its certification portfolio, so confirm the exam's current status when you book.

Before you enroll

You should be developing applications on Azure already and have practical exposure to Cosmos DB. This is a practice bank for testing readiness, not an introduction to NoSQL or to Azure. Every question here is original and written from the current published skills outline. These are not brain dumps. This course is independent and is not affiliated with, endorsed by, or sponsored by Microsoft. Microsoft, Azure and Azure Cosmos DB are trademarks of Microsoft Corporation.