C100DEV Drivers, Tools, Transactions, and Search Practice Question
A developer is using the MongoDB Node.js driver to perform a multi-document transaction that includes a read operation followed by a write operation. The developer wants to ensure that the read sees a consistent snapshot of the data and that the write is atomic with the read. Which of the following read concerns should be used for the read operation within the transaction?
⚠ Common exam trap
The trap here is assuming that 'majority' read concern is sufficient for transactions, but it does not provide a consistent snapshot across multiple operations.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
snapshot
Within a multi-document transaction, the read concern must be 'snapshot' to ensure a consistent snapshot of the data for all operations in the transaction. This provides the required isolation and atomicity. Other read concerns like 'local', 'majority', or 'linearizable' do not provide the same guarantees within a transaction and may not be supported.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
snapshot
Why this is correct
readConcern: 'snapshot' is specifically designed for multi-document transactions. It provides a consistent snapshot of the data at the start of the transaction, ensuring that all reads within the transaction see the same data. This meets the developer's requirement for a consistent snapshot and atomicity with the write.
- ✗
linearizable
Why it's wrong here
readConcern: 'linearizable' provides the strongest consistency guarantees for reads, ensuring that the read reflects the latest committed write. However, it is not supported within multi-document transactions. Using it would cause an error. Therefore, it cannot be used in this scenario.
- ✗
local
Why it's wrong here
readConcern: 'local' returns data from the local node without guaranteeing that it has been replicated to a majority. It does not provide a consistent snapshot across the transaction. Within a transaction, using 'local' would not ensure that the read sees a consistent view of the data, potentially leading to inconsistencies. Therefore, it is not suitable for this scenario.
- ✗
majority
Why it's wrong here
readConcern: 'majority' ensures that the data read has been acknowledged by a majority of replica set members. While this provides stronger durability guarantees, it does not provide a consistent snapshot across multiple operations in a transaction. For transactions, the appropriate read concern is 'snapshot' to ensure a consistent view. Thus, 'majority' is not the best choice here.
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official MongoDB exam blueprint
This C100DEV practice question is part of Courseiva's free MongoDB certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the C100DEV exam.