C100DBA Exam Dumps - MongoDB Certified DBA Associate Questions and Answers

MongoDB stores records as BSON documents. BSON, short for Binary JSON, is a binary serialization format that preserves the JSON-like document model while supporting a richer set of data types required by database applications. Mongosh commonly displays documents using JavaScript or Extended JSON-like notation, which is why JSON is a tempting distractor, but the native stored representation is BSON. BSON supports types such as ObjectId, dates, binary data, timestamps, Decimal128, 32-bit and 64-bit integers, arrays, embedded documents, and other values that standard JSON does not represent natively. Base64 is an encoding technique often used to render binary data as text and is not MongoDB ' s document storage format. XML is also unrelated to MongoDB ' s native representation. Understanding BSON is fundamental for database administrators because document-size limits, type comparisons, index keys, serialization behavior, and driver interoperability all depend on BSON semantics. The flexible document model allows fields to contain scalar values, nested documents, and arrays within the same record structure. Therefore the encoded format used by MongoDB to store documents is BSON, making option C correct.

Study Guide reference/topic:MongoDB Architecture and Core Operations - BSON, document structure, data types, and JSON/BSON distinctions.

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logLevel is a MongoDB server parameter, and server parameters are retrieved through the administrative getParameter database command. The documented and unambiguous mongosh form is db.adminCommand({ getParameter: 1, logLevel: 1 }), which executes the command against the admin database and requests the current value of logLevel. The first numeric value activates the command, while the logLevel field identifies the parameter to return. Options B and C refer to a db.getParameter() helper that is not the documented interface. Option A uses db.runCommand() without explicitly switching to the admin database. Because getParameter is an administrative command, db.adminCommand() is the correct and reliable form among the choices. Administrators use server parameters to inspect and, where supported, tune aspects of mongod or mongos behavior. logLevel controls global diagnostic verbosity, while component-specific verbosity can be managed through the logging configuration. For this question, option D precisely matches the expected administrative syntax. Checking the current value before changing logging settings is also a sound operational practice during troubleshooting.

Study Guide reference/topic:Performance Monitoring and Tuning - runtime server parameters, logging configuration, and getParameter.

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MongoDB read preference controls which replica-set members are eligible to serve read operations. The mode secondary sends reads only to eligible secondary members. If no suitable secondary is available, the read fails rather than falling back to the primary. That strict behavior is exactly what the question asks for. secondaryPreferred, option A, normally routes reads to secondaries but can use the primary when no suitable secondary is available, so it does not guarantee that every read is served by a secondary. Options B and C are not valid MongoDB read preference mode names. Secondary reads are useful for specific workloads, but DBAs must account for asynchronous replication: a secondary can lag the primary, so data returned from a secondary may be stale relative to the latest acknowledged primary write. MongoDB provides additional controls such as tag sets and maximum staleness settings to restrict which secondary members are considered acceptable. When the explicit requirement is to direct all reads away from the primary and exclusively to secondary members, secondary is the correct read preference. Therefore option D is correct.

Study Guide reference/topic:Cluster Reliability and Data Resilience - replica-set read preferences, secondary reads, and staleness.

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