C100DEV Drivers, Tools, Transactions, and Search Practice Question
A developer needs to perform a point-in-time backup of a MongoDB replica set while the database remains online and serving reads and writes. Which MongoDB Database Tool is designed for this task?
⚠ Common exam trap
A common mix-up: candidates confuse an export utility with a backup tool, since mongoexport also reads data from a live deployment but cannot support point-in-time recovery.
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
✓
mongodump with --oplog
mongodump with --oplog is the MongoDB Database Tool that captures both data and oplog entries during a live dump, enabling point-in-time restore. It runs against a running replica set without downtime. mongoexport lacks oplog capture, mongorestore applies dumps rather than creating them, and mongostat is a monitoring tool, so none of those meet the backup requirement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
mongostat with --discover
Why it's wrong here
mongostat is a monitoring utility that reports operation counters and latency statistics for a running deployment. It does not read or write data files and cannot produce a backup of any kind. The --discover option only helps it find members of a replica set to monitor. Using it for point-in-time backup misunderstands its purpose entirely, as it provides observability rather than data protection.
- ✗
mongorestore with --archive
Why it's wrong here
mongorestore is a restore utility, not a backup tool. The --archive flag controls reading from a single archive file produced by mongodump. Running mongorestore against a live database would not create a backup; it would apply an existing dump. Because the scenario asks for creating a point-in-time backup while online, this tool is the wrong direction in the backup and restore workflow.
- ✗
mongoexport with --query
Why it's wrong here
mongoexport produces JSON or CSV exports of collection data, not a restorable point-in-time backup. It does not capture the oplog, so it cannot support point-in-time recovery. Using --query limits which documents are exported, which further departs from a full backup. While mongoexport can run against a live deployment, it lacks the oplog capture that makes point-in-time restoration possible.
- ✓
mongodump with --oplog
Why this is correct
mongodump with --oplog captures the data plus the oplog entries that occurred during the dump, enabling a point-in-time restore to a specific moment. It runs against a live replica set without requiring downtime, which matches the requirement. The resulting dump can be restored with mongorestore --oplogReplay to reach a consistent point in time, making this the correct tool for online point-in-time backups.
About these practice questions
This C100DEV question is part of Courseiva's 259-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 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.