C100DBA Sharding Practice Question
Which TWO statements accurately describe the behavior and management of orphaned documents in a MongoDB sharded cluster? Choose 2 answers.
⚠ Common exam trap
Candidates assume that once a chunk migrates, all data is instantly and completely purged from the source shard without needing any manual or background cleanup.
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
✓
Orphaned documents are documents that remain on a shard after a chunk has been migrated away to another node in the cluster.
Orphaned documents are leftover data chunks remaining on a source shard after a chunk migration fails to complete cleanly or before a background cleanup process runs. Understanding how MongoDB handles orphaned documents helps DBAs troubleshoot storage utilization issues and run cleanup tasks safely without risking valid data.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Orphaned documents are documents that remain on a shard after a chunk has been migrated away to another node in the cluster.
Why this is correct
Orphaned documents are documents that remain on a shard after a chunk has been migrated away to another node in the cluster. During chunk migrations, source shards retain copies temporarily until cleanup routines safely remove them once migration confirmation is verified.
- ✓
Administrators can run the cleanupOrphaned command against shard mongod instances to remove leftover documents outside active chunk ranges.
Why this is correct
Administrators can run the cleanupOrphaned command against shard mongod instances to remove leftover documents outside active chunk ranges. Running cleanupOrphaned scans shard data files for documents falling outside current chunk ranges assigned to that specific shard and deletes them to reclaim disk space.
- ✗
Orphaned documents are automatically indexed by the query router and included in all scatter-gather query results by default.
Why it's wrong here
Orphaned documents are automatically indexed by the query router and included in all scatter-gather query results by default. Query routers filter out orphaned documents automatically during query execution, ensuring they never contaminate application result sets.
- ✗
The cluster balancer deletes orphaned documents simultaneously across all shards during every active migration window.
Why it's wrong here
The balancer never deletes orphaned documents; it migrates chunks between shards, and orphans are cleaned by the range deleter on each shard after metadata changes. It is tempting because the balancer does coordinate chunk migration, but deletion is a separate background process, not a simultaneous cluster-wide action.
- ✗
Orphaned documents prevent the config server from performing routine replica set elections until they are manually purged.
Why it's wrong here
Orphaned documents prevent the config server from performing routine replica set elections until they are manually purged. Orphaned documents reside exclusively on shard storage engines and have zero impact on config server metadata management or replica set elections.
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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.