C100DBA Philosophy and Features Practice Question
How does the 'w: majority' write concern align with the philosophy of data reliability in MongoDB?
⚠ Common exam trap
Many candidates mistakenly believe 'w: majority' ensures the data is written to all nodes in the cluster, confusing it with absolute synchronization rather than a majority quorum of voting members.
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 ensures the data is durable on a majority of nodes.
The 'w: majority' write concern ensures that a write operation is acknowledged only after it has been replicated to a majority of nodes in the replica set. This philosophy prioritizes data durability and consistency over the absolute lowest latency. By requiring a majority, MongoDB ensures that even if a primary node fails immediately after a write, the data persists on other nodes, minimizing the window for data loss during failover.
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 the write is applied to all shards.
Why it's wrong here
Write concern defines the level of acknowledgment for a write operation within a single replica set. It does not control cross-shard replication or global cluster behavior. It is localized to the replica set that is the target of the specific write command.
- ✓
It ensures the data is durable on a majority of nodes.
Why this is correct
By requiring acknowledgment from a majority of the replica set nodes, MongoDB provides a high degree of confidence that the data is not lost if the primary fails. This aligns with the philosophy of balancing write performance with data safety and persistence.
- ✗
It optimizes for the fastest possible write performance.
Why it's wrong here
Waiting for a majority of nodes to acknowledge a write adds network latency compared to 'w: 1', which only requires the primary to acknowledge. Therefore, 'w: majority' is a trade-off that sacrifices raw write throughput for significantly increased data durability and consistent safety guarantees.
- ✗
It forces an immediate sync to the storage disk.
Why it's wrong here
The write concern specifies acknowledgment levels, not the underlying storage engine's disk flushing behavior. Disk syncing is controlled by the 'j' (journal) option. These are separate concepts; one relates to network replication, while the other relates to the durability of the local storage engine.
About these practice questions
This C100DBA question is part of Courseiva's 222-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
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.