C100DBA Application Administration Practice Question
What is the purpose of the 'write concern' in MongoDB?
⚠ Common exam trap
Candidates often confuse write concern with read concern, mistakenly believing it dictates how data is retrieved from secondaries rather than acknowledging how the primary confirms the write operation.
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
✓
To define the durability and replication requirements for a write.
Write concern determines the level of acknowledgement requested from the database for write operations. It is a critical setting for balancing performance against data durability. By choosing the right write concern, developers can ensure that their application meets its specific data safety requirements, whether that means waiting for confirmation from a single node or guaranteeing that the write has been replicated across a majority of the cluster nodes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
To specify which primary node the write should be directed to.
Why it's wrong here
The client driver and the cluster configuration handle node routing automatically. The write concern has nothing to do with selecting a target node; it is solely about the level of acknowledgement the application expects from the server after the write operation has been processed.
- ✓
To define the durability and replication requirements for a write.
Why this is correct
Write concern allows developers to configure how many replica set members must acknowledge a write before it is considered successful. This provides fine-grained control over durability and consistency, enabling developers to trade off between write performance and the level of data safety they require.
- ✗
To encrypt the data being written to the database.
Why it's wrong here
Encryption is a security feature handled by TLS/SSL or encryption-at-rest features like WiredTiger encryption. The write concern is entirely unrelated to data security or encryption and is strictly used for controlling the acknowledgement behavior of write operations within the MongoDB replica set.
- ✗
To automatically compress the data before it reaches the disk.
Why it's wrong here
Data compression is managed by the storage engine and happens transparently when data is written to the disk. Write concern is an application-level configuration for acknowledgement and has no impact on how the data is stored or compressed on the physical storage media.
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.