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Question 301

Which command changes a collection’s shard key?

1. changeShardKey()
2. updateShardKey()
3. reshardCollection
4. replaceShardKey()

Correct Answer: 3

Explanation:

The reshardCollection command is used to change the shard key of an existing sharded collection. Resharding can redistribute data according to a new shard key when the original key no longer provides suitable distribution or query targeting. MongoDB performs the process while maintaining the collection’s availability according to the supported resharding behavior. Choosing an appropriate shard key remains important because it influences data distribution, scalability, and query routing. The other listed commands are not MongoDB commands for changing an existing collection’s shard key.

Question 302

Which command adds fields to an existing shard key?

1. refineCollectionShardKey
2. extendShardKey
3. expandCollectionKey
4. modifyShardPattern

Correct Answer: 1

Explanation:

The refineCollectionShardKey command adds one or more fields to an existing shard key pattern. Refining a shard key can improve data distribution or provide more precise targeting for queries without replacing the entire shard-key strategy through a complete resharding operation. The refined pattern must follow MongoDB’s shard-key requirements. This capability is useful when an existing key needs additional granularity as application data or query patterns evolve. extendShardKey, expandCollectionKey, and modifyShardPattern are not the standard MongoDB commands for refining a shard key.

Question 303

Which helper moves a specific chunk between shards?

1. sh.moveData()
2. sh.relocateChunk()
3. sh.transferChunk()
4. sh.moveChunk()

Correct Answer: 4

Explanation:

The sh.moveChunk() helper is used to move a chunk from one shard to another. Chunk movement can help administrators address uneven data distribution or manually relocate data when managing a sharded cluster. MongoDB’s balancer normally handles balancing automatically, but administrative chunk movement can be useful for specific maintenance scenarios. The operation identifies the relevant namespace and chunk range along with the destination shard. The other helpers listed are not standard MongoDB shell helpers for moving chunks between shards.

Question 304

Which helper splits a chunk at an explicit shard-key value?

1. sh.splitRange()
2. sh.splitAt()
3. sh.divideChunk()
4. sh.breakAt()

Correct Answer: 2

Explanation:

The sh.splitAt() helper splits a chunk at a specified shard-key value. This creates separate chunk ranges from an existing chunk and can be useful when administrators need more granular data distribution. Explicit splitting can help prepare a collection for balancing or address distribution patterns where automatic chunk management does not immediately provide the desired boundaries. The supplied split point must correspond to a valid shard-key value for the collection. sh.splitRange(), sh.divideChunk(), and sh.breakAt() are not the standard shell helpers for this operation.

Question 305

Which helper splits a chunk containing a query value?

1. sh.splitFind()
2. sh.findSplit()
3. sh.splitQuery()
4. sh.divideFind()

Correct Answer: 1

Explanation:

The sh.splitFind() helper splits the chunk that contains a specified shard-key value. Instead of explicitly supplying a complete chunk boundary, the helper identifies the relevant chunk using the provided shard-key query and performs the split. This can be convenient when administrators know a value associated with an area of the key space that needs greater granularity. It is different from sh.splitAt(), where an explicit split point is supplied. The other listed helper names are not standard MongoDB shell methods for locating and splitting a chunk.

Question 306

Which helper combines adjacent chunks on one shard?

1. sh.joinChunks()
2. sh.combineRanges()
3. sh.mergeRanges()
4. sh.mergeChunks()

Correct Answer: 4

Explanation:

The sh.mergeChunks() helper combines contiguous chunks that belong to the same shard. Merging can reduce the number of chunk ranges and simplify chunk distribution when excessive splitting has created many small chunks. The chunks must satisfy MongoDB’s requirements for merging, including being adjacent and located on the same shard. Chunk management should be performed carefully because chunk boundaries influence balancing and routing. sh.joinChunks(), sh.combineRanges(), and sh.mergeRanges() are not the standard MongoDB shell helper used for merging chunks.

Question 307

Which helper reports sharded data distribution details?

1. sh.getShardedDataDistribution()
2. sh.showDataBalance()
3. sh.inspectShardData()
4. sh.dataDistribution()

Correct Answer: 1

Explanation:

The sh.getShardedDataDistribution() helper provides information about how sharded data is distributed across the cluster. It can help administrators examine collection distribution and understand how data is spread among shards. Such information is useful when investigating uneven distribution, planning capacity, or evaluating the effects of shard-key choices. Distribution information should be interpreted together with workload characteristics because even physical distribution does not automatically guarantee optimal query performance. The other helper names are not the standard MongoDB method for retrieving sharded data distribution information.

Question 308

Which command reports the current status of the balancer for a collection?

1. sh.collectionBalancer()
2. balancerCollectionStatus
3. sh.checkBalancerCollection()
4. getCollectionBalancer

Correct Answer: 2

Explanation:

The balancerCollectionStatus command reports balancing-related information for a sharded collection. It can help administrators determine whether balancing is active or whether a collection has conditions affecting balancing behavior. This is particularly useful when investigating why data movement is not occurring as expected. Collection-specific balancing behavior can involve settings and restrictions beyond the cluster-wide balancer state. sh.collectionBalancer(), sh.checkBalancerCollection(), and getCollectionBalancer are not the standard MongoDB command names for obtaining this collection-level balancing status.

Question 309

What feature can combine multiple indexes for one query plan?

1. Index intersection
2. Index federation
3. Index chaining
4. Index aggregation

Correct Answer: 1

Explanation:

Index intersection allows MongoDB to use multiple indexes together when producing a query execution plan. Instead of depending on a single compound index that covers every useful predicate, the query planner may combine index information from separate indexes when that provides an efficient plan. Whether intersection is selected depends on the query shape, available indexes, and estimated execution costs. It is not guaranteed for every query. Index intersection can therefore complement, but does not universally replace, carefully designed compound indexes. The other terms are not the standard MongoDB feature names for combining indexes in query planning.

Question 310

Which command changes the index build commit quorum?

1. configureIndexBuild
2. updateIndexQuorum
3. setIndexCommitQuorum
4. changeBuildConsensus

Correct Answer: 3

Explanation:

The setIndexCommitQuorum command changes the commit quorum for an index build. The commit quorum determines how many voting replica-set members must report successful index builds before the index build can commit. This provides administrators with control over index-build coordination in replica sets. The quorum can be adjusted when operational circumstances require a different level of participation from voting members. Because index builds affect replica-set resources, administrators should understand the availability and consistency implications before changing the quorum. The other commands are not standard MongoDB commands for this setting.

Question 311

Which command provides the initial server handshake information?

1. hello
2. serverHello
3. handshake
4. identifyServer

Correct Answer: 1

Explanation:

The hello command provides information that clients use when establishing or monitoring a MongoDB server connection. Its response can include topology-related details such as server type, replica-set information, and connection capabilities. Modern MongoDB drivers use the hello protocol to discover server topology and determine appropriate communication behavior. This information is especially important in replica sets and sharded environments, where clients need to understand the role and capabilities of connected servers. serverHello, handshake, and identifyServer are not the standard MongoDB command names for this protocol.

Question 312

Which connection option enables driver load-balanced mode?

1. balancedConnection
2. loadBalanced
3. driverBalance
4. connectionBalancer

Correct Answer: 2

Explanation:

The loadBalanced connection option enables load-balanced mode for supported MongoDB deployments and drivers. In this mode, the driver can distribute client connections through a load-balancing architecture rather than treating the topology as a traditional direct server selection environment. The option is configured in the MongoDB connection string or driver configuration depending on the client language. Its availability and behavior depend on the deployment and driver version. balancedConnection, driverBalance, and connectionBalancer are not the standard MongoDB connection option names.

Question 313

Which setting limits how long a transaction may remain active?

1. transactionLifetimeLimitSeconds
2. transactionTimeoutLimit
3. maxTransactionAge
4. transactionDurationLimit

Correct Answer: 1

Explanation:

The transactionLifetimeLimitSeconds setting controls the maximum lifetime of a transaction. MongoDB uses this limit to prevent transactions from remaining open indefinitely and retaining resources for excessive periods. Long-running transactions can affect resource usage and may increase pressure on storage and replication systems. Applications should therefore keep transactions focused and complete them promptly. The configured lifetime applies at the server or deployment level according to MongoDB’s supported configuration mechanisms. transactionTimeoutLimit, maxTransactionAge, and transactionDurationLimit are not the standard MongoDB parameter names for transaction lifetime.

Question 314

Which option limits time spent committing a transaction?

1. commitTimeout
2. transactionCommitLimit
3. commitDeadline
4. maxCommitTimeMS

Correct Answer: 4

Explanation:

The maxCommitTimeMS option limits the amount of time MongoDB should spend on the commit portion of a transaction. It is distinct from the overall transaction lifetime because the setting specifically applies to the commit operation. This can be useful when applications need bounded commit behavior and want to avoid waiting indefinitely during transaction finalization. The option should not be confused with general socket or server-selection timeouts, which govern different stages of client-server communication. commitTimeout, transactionCommitLimit, and commitDeadline are not the standard MongoDB transaction option names.

Question 315

Which session feature keeps operations causally ordered?

1. Transaction pinning
2. Read isolation
3. Causal consistency
4. Snapshot locking

Correct Answer: 3

Explanation:

Causal consistency allows related operations within a client session to observe results in an order consistent with their causal relationships. This is useful when an application performs one operation and then expects a subsequent read to reflect the effects that causally precede it. MongoDB sessions can support causal consistency when configured appropriately. This behavior differs from transaction isolation, which concerns the visibility and atomicity of operations within a transaction. Causal consistency is particularly useful for distributed applications where operations may interact with different members of a replica set.

Question 316

Which read concern requests a linearizable read from the primary?

1. linearizable
2. ordered
3. serializable
4. synchronous

Correct Answer: 1

Explanation:

The linearizable read concern provides the strongest single-document read semantics available for supported primary reads. It ensures that the read reflects the most recent successful write according to the required linearizable ordering. This behavior is intended for workloads where an application needs strong guarantees about observing the latest committed state from the primary. It can involve additional coordination and latency compared with weaker read concerns. ordered, serializable, and synchronous are not MongoDB read concern names that provide this specific behavior.

Question 317

Which utility displays live server operation statistics?

1. mongoops
2. mongostat
3. mongosummary
4. mongoperf

Correct Answer: 2

Explanation:

The mongostat utility provides a real-time view of MongoDB server activity. It reports continuously changing operational metrics such as insert, query, update, delete, and command activity, along with connection and other server statistics. Administrators can use it for quick observation of workload behavior and for identifying periods of unusually high activity. It is intended as a monitoring utility rather than a replacement for detailed diagnostic analysis. mongoops, mongosummary, and mongoperf are not the standard MongoDB command-line utility names for this live server-statistics view.

Question 318

Which utility reports collection-level read and write activity?

1. mongocollect
2. mongotop
3. mongoread
4. mongowatch

Correct Answer: 2

Explanation:

The mongotop utility provides information about the amount of time MongoDB spends reading from and writing to collections. It is useful for observing collection-level activity and identifying collections that are receiving substantial workload. Administrators can use this information as an initial monitoring signal when investigating workload patterns. It differs from mongostat, which focuses more broadly on server activity metrics. mongocollect, mongoread, and mongowatch are not the standard MongoDB utilities used to display collection read and write activity.

Question 319

What facility continuously captures diagnostic data?

1. FTDC
2. DTS
3. DiagStream
4. ServerTrace

Correct Answer: 1

Explanation:

FTDC, or Full-Time Diagnostic Data Capture, is MongoDB’s mechanism for collecting diagnostic information continuously. It records server metrics that can help administrators and support teams investigate performance problems, resource pressure, and unusual server behavior. The collected information is designed to provide historical context that may not be available from a snapshot taken after a problem occurs. FTDC operates as part of MongoDB’s diagnostic infrastructure and should be considered when reviewing diagnostic data from a deployment. DTS, DiagStream, and ServerTrace are not the standard MongoDB facility names for this purpose.

Question 320

Which utility creates a binary database backup?

1. mongodump
2. mongoarchive
3. mongobackup
4. dbdump

Correct Answer: 1

Explanation:

The mongodump utility creates a binary export of MongoDB database data that can later be restored with mongorestore. It is commonly used for logical backups, migrations, testing, and moving selected databases or collections between environments. Because it produces a logical representation rather than a filesystem-level snapshot, backup planning should consider the size of the dataset and the desired recovery objectives. For larger production environments, other MongoDB backup approaches may also be appropriate. mongoarchive, mongobackup, and dbdump are not the standard MongoDB utility names for creating this type of backup.