C100DBA Philosophy and Features Practice Question
What is the consequence of MongoDB's 'write concern' in a distributed environment?
⚠ Common exam trap
Candidates often view write concern only as a speed setting. They fail to understand that it is fundamentally a trade-off between performance latency and data durability guarantees.
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
✓
It allows developers to balance latency and durability.
Write concern determines the level of acknowledgment required from the replica set before a write operation is considered successful. A higher write concern ensures stronger data durability by requiring the write to reach a majority of nodes, thereby preventing data loss in the event of a primary failure. This highlights MongoDB's philosophy of allowing developers to choose the right balance between write latency and data safety based on specific application requirements.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
It guarantees that all reads are always from the primary.
Why it's wrong here
Write concern relates to the persistence of write operations, not the source of read operations. Read preference settings determine which nodes can serve read requests. You can read from secondaries even if write concern is set to acknowledge only the primary, provided the application handles eventual consistency.
- ✓
It allows developers to balance latency and durability.
Why this is correct
By configuring write concern (e.g., 'w: 1', 'w: majority'), developers explicitly define the trade-off between performance and safety. A 'w: 1' setting is faster but carries a risk of rollback, while 'w: majority' is safer but adds latency due to network round-trips required for replication acknowledgment.
- ✗
It automatically enables sharding across regions.
Why it's wrong here
Write concern is a configuration setting for individual operations or the cluster, not an infrastructure provisioning feature. It does not control data distribution or sharding. Sharding is a separate architectural deployment pattern that must be configured through cluster management, independently of the write acknowledgment settings used for data durability.
- ✗
It forces every node to process every write request.
Why it's wrong here
Write concern only specifies how many nodes must acknowledge a write for the client to receive a success message. It does not require every node in a cluster to process the write. The replication process happens asynchronously or synchronously based on the configuration, but it is not a blocking broadcast.
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 C100DBA 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 C100DBA exam.