C100DBA Exam Dumps - MongoDB Associate Database Administrator(Based on MongoDB 6.0 and 7.0+)

mongosh, the MongoDB Shell, is the interactive command-line environment used to connect to MongoDB deployments and perform administrative and data operations. Through mongosh, a DBA can run CRUD queries, aggregation pipelines, user and role administration, replica-set commands, server diagnostics, index operations, and many other management tasks. mongod, option B, is the MongoDB database server process itself; it stores data and serves requests but is not the interactive administration client. mongostat, option C, is a monitoring utility that reports a concise stream of server activity metrics such as operation rates, memory, connections, and queue information. mongotop, option D, reports time spent reading and writing data by namespace and is likewise a diagnostic utility rather than a general administration shell. DBAs may also use MongoDB Compass, Atlas interfaces, Ops Manager, or automation tooling depending on the deployment, but among these four command-line tools, mongosh is the one intended for broad interactive access and administration. Therefore option A is correct.

Study Guide reference/topic:MongoDB Architecture and Core Operations - MongoDB Shell, administration tools, server processes, and monitoring utilities.

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A hidden index remains physically present and continues to be maintained as documents are inserted, updated, or deleted, but the query planner does not consider that index when choosing normal execution plans. This makes hidden indexes especially useful for safely testing whether an index can be removed. An administrator can hide the index and observe production query behavior as though the index were absent. If performance or plan quality degrades, the index can be unhidden immediately without rebuilding it because MongoDB has continued to maintain it in the background. Option A is incorrect because a hidden index is still an index and is not simply removed from index statistics. Option B is also incorrect; hiding an index can actually force collection scans or alternative plans if that index was previously important. Option D misunderstands the feature entirely: hiding an index has no effect on document visibility. Hidden indexes are therefore a risk-reduction mechanism for index lifecycle management, especially before dropping an index in a production environment. Option C accurately states that purpose.

Study Guide reference/topic:Indexing and Query Optimization - hidden indexes, query planner behavior, and safe index-removal testing.

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