Sample 1 · Concept
When using `insertMany()` with its default settings, what happens if one of the documents in the array causes a duplicate key error?
Pick one, then submit.
MongoDBAssociateHands-on lab
C100DEVMongoDB Associate Developer
1,059vetted practice questions
53questions on the exam
75minutes
80%to pass
Start free, then add this exam Start on the free tier, then add this exam from the plan picker inside the app.
Prep smarter™
The exam
What C100DEV tests
Validates the knowledge and hands-on skills a developer needs to build applications on MongoDB — the document model and BSON types, CRUD operations and queries, the aggregation framework, indexing for performance, data modeling, Atlas tooling, and using a MongoDB driver in your language of choice.
Who it is for
Built for associate-level candidates
Application developers using MongoDB as the backing database, with software engineering experience in any language and hands-on experience performing day-to-day MongoDB operations. The Drivers section is taken in your chosen language (C#, Java, Node.js, PHP, or Python).
Hands-on lab
Practice on a real cluster, not a quiz about one.
Write actual queries, aggregations and updates against a live MongoDB sandbox and get graded on what they return, not on which option you picked. CRUD tasks run in a disposable collection seeded for each attempt.
Stuck? Winston’s hints come in three rungs, and your score reflects how much help you took.
NudgeA first hint points at the idea without giving it away.
CorrectThe second quotes your own fragment and fixes the syntax.
ReferenceThe third shows the answer with one blank left for you.
A real task, graded on what the query returns.
What it covers
The official domains, weighted as the exam weights them.
Your readiness map in the app is organised the same way, so what you see here is exactly what you study against.
- Overview & the Document Model8%
- CRUD Operations51%
- Indexes17%
- Data Modeling4%
- Tools & Tooling2%
- Drivers18%
What Preppio gives you
Signal, not vibes.
1,059 questions
Across every domain above, in 3 formats: concept, scenario, multi-select, plus a hands-on lab. Each one explains why the right answer is right and every distractor wrong.
A readiness map
Per domain, whether you are ready, weak, or not started — the same domains and weights as the exam itself.
Winston
Your study partner. He tracks where you are weak and drills exactly that, instead of serving you what you already know.
Try one
One of each format C100DEV uses, from the same bank.
Answer on the page. The explanation appears when you submit; use Next to move through the formats.
1 of 3
Study links
Official material
FAQ
The things people ask about C100DEV
How many questions are on the C100DEV exam, and how long is it?
53 questions in 75 minutes.
What score do you need to pass C100DEV?
80%.
What does C100DEV cover?
6 domains, weighted as the exam weights them: Overview & the Document Model (8%), CRUD Operations (51%), Indexes (17%), Data Modeling (4%), Tools & Tooling (2%) and Drivers (18%). Your readiness map in the app is organised by the same domains, so what you study against is what the exam tests.
What question formats does C100DEV use?
Three formats: concept, scenario and multi-select. The practice questions use every one of them, and the sample on this page shows one of each.
Is C100DEV free on Preppio.ai?
C100DEV is on the Single, Dual and All Access plans. You start on the free tier and add it from the plan picker inside the app. Three fundamentals exams (AZ-900, CLF-C02 and CDL) are always free, and the sample on this page is free to try.
Does C100DEV prep include a hands-on lab?
Yes. C100DEV has a graded hands-on lab inside the exam prep: you run the work for real and it is graded as you go, alongside the practice questions.
Where do the C100DEV practice questions come from?
Every question is generated from the exam's published objectives, then checked for accuracy, answer key and explanation before it is served. Nothing is copied from any exam, questions rotate by how often they have been seen, and they are retired when the objectives change.