C100DBA Philosophy and Features Practice Question
A healthcare provider is building a patient portal that must remain available even if a data center loses power. The operations team wants the database to continue accepting writes during a single-region outage. Which MongoDB philosophy directly enables this resilience?
⚠ Common exam trap
A common mix-up: candidates confuse backup and disaster recovery with high availability, when only automatic failover with durable writes meets continuous write availability.
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
✓
Automatic failover through replica sets with majority write concern
Replica sets provide automatic failover by electing a new primary when the current one fails, and majority write concern ensures that acknowledged writes are durable across a majority of members. Together, they allow the portal to keep accepting writes during a single-region outage without manual intervention.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Relying on periodic logical backups to a cold standby server
Why it's wrong here
Periodic logical backups to a cold standby server do not provide continuous availability. If the primary data center fails, the standby must be manually restored or promoted, causing significant downtime. Backups are essential for disaster recovery but do not meet the requirement of continuing to accept writes during an outage.
- ✓
Automatic failover through replica sets with majority write concern
Why this is correct
Replica sets maintain multiple copies of data and automatically elect a new primary if the current one becomes unavailable. Majority write concern ensures that writes are acknowledged by a majority of voting members before returning success, so acknowledged data survives failover. This combination directly provides the continuous write availability and resilience the portal needs.
- ✗
Deploying a standalone mongod instance in each region with application-level conflict resolution
Why it's wrong here
Standalone instances in each region with application-level conflict resolution push the complexity of consistency and conflict handling onto the application. This approach lacks MongoDB's built-in replication and automatic failover, and it can lead to data conflicts that are hard to resolve. It does not provide the seamless resilience expected from a replica set.
- ✗
Storing all patient data on a single replicated node with manual failover
Why it's wrong here
A single replicated node with manual failover cannot automatically recover from a data center outage. Manual intervention would introduce downtime, violating the requirement to continue accepting writes during an outage. This approach also lacks the automatic election and redundancy that a proper replica set provides.
About these practice questions
Courseiva writes every C100DBA question from scratch — 222 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or 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.