20+ practice questions focused on Sharding — one of the most tested topics on the MongoDB Certified DBA Associate exam. Each question includes a detailed explanation so you learn why the right answer is correct.
Start Sharding PracticeWhen selecting a shard key for a new collection, which TWO of the following rules must be followed?
Explanation: Shard key selection is one of the most critical decisions in MongoDB architecture. A shard key must be part of an index and, for versions prior to 4.2, its value could not be changed. Understanding these constraints ensures that the collection can be successfully partitioned and that the database can efficiently route queries and manage data distribution across the shards.
Starting in MongoDB 4.4, you can refine a shard key by adding suffix fields to the existing key. Which TWO conditions must be met for this operation to succeed?
Explanation: Refining a shard key allows for finer-grained data distribution when the original key lacks sufficient cardinality. Unlike changing a shard key entirely, refinement is a non-disruptive operation that adds fields to the existing key. This capability is essential for evolving schemas and addressing performance issues that arise as the volume and distribution of data change.
What occurs when a chunk in a sharded collection exceeds the maximum configured chunk size?
Explanation: MongoDB automatically splits chunks when they reach a certain size, usually 64MB, to ensure that data can be distributed effectively across shards. Splitting is a metadata-only operation that occurs on the primary shard of the replica set containing the chunk. Understanding this process is vital for DBAs to manage cluster growth and prevent the creation of jumbo chunks.
Which TWO actions should a database administrator perform before executing the shardCollection command on an existing populated MongoDB collection? Choose 2 answers.
Explanation: Sharding an existing populated collection requires creating the supporting index first to provide the routing foundation, and ensuring the database is explicitly enabled for sharding. Performing these prerequisites avoids runtime failures and ensures the cluster balancer can immediately initialize and distribute the initial data chunks across the configured shards without throwing administrative exceptions.
Which THREE statements are true regarding the behavior and mechanics of the MongoDB cluster balancer? Choose 3 answers.
Explanation: The MongoDB balancer runs as a background process coordinated by the primary config server, moving chunks between shards when migration thresholds are met. Knowing balancer mechanics helps DBAs troubleshoot uneven data distributions, plan maintenance windows, and manage cluster resources effectively without causing unexpected performance degradation.
+15 more Sharding questions available
Practice all Sharding questions1. Baseline your knowledge
Start with 10 questions to gauge your current understanding of Sharding. This tells you whether you need a concept refresher or just practice.
2. Review every explanation
For each question — right or wrong — read the full explanation. Understanding why an answer is correct is more valuable than knowing the answer itself.
3. Focus on exam traps
Sharding questions on the C100DBA frequently use trap wording. Look for subtle differences in answers that test your precision, not just general knowledge.
4. Reach 80% consistently
Do repeated sessions until you score 80%+ three times in a row. Then move to mixed-mode practice to test cross-topic recall under realistic conditions.
The exact number varies per candidate. Sharding is tested as part of the MongoDB Certified DBA Associate blueprint. Practicing with targeted Sharding questions ensures you can handle any format or difficulty that appears.
Yes. Courseiva provides free C100DBA practice questions across all exam topics and domains. The platform includes topic-based practice, mock exams, missed-question review, bookmarked questions, and readiness tracking — no account required.
Difficulty is subjective, but Sharding is a high-priority exam concept tested in multiple ways — direct recall, scenario analysis, and command-output interpretation. Consistent practice is the best way to build confidence.
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