Pass the MongoDB Certified DBA Associate C100DBA Questions and answers with Dumpstech

Transport Layer Security protects MongoDB network communications while data travels between clients and servers and, when configured, between MongoDB deployment members. Its core purpose is therefore encryption of data in transit. TLS helps prevent passive interception and tampering and also supports certificate-based identity validation. It is separate from encryption at rest, which protects files on storage media, and separate from Queryable Encryption or client-side field encryption, which protects selected application data before it reaches the server. Option A is unrelated: backup and restore operations use snapshot, managed backup, or database-tool mechanisms. Option B describes the objective of replication, elections, and redundant deployment architecture, not TLS. Option C is also incorrect; TLS is a security control, not a query-optimization mechanism, and cryptographic processing can add some overhead rather than improving query execution. A secure MongoDB deployment normally combines TLS with strong authentication, least-privilege authorization, appropriate network exposure controls, auditing, and storage or field-level encryption as required. For the specific question, enabling TLS provides encryption for data moving across the network, making option D correct.

Study Guide reference/topic:Security, Networking, and Encryption - TLS/SSL, transport encryption, certificates, and network security.

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A replica-set secondary maintains a replicated copy of the primary ' s dataset. The primary records data-changing operations in its oplog, and secondary members continuously copy and apply those oplog entries asynchronously to keep their data synchronized. This redundancy allows an eligible secondary to participate in an election and potentially become primary if the current primary becomes unavailable. mongos, option B, is the query-routing process used in a sharded cluster; it does not store an application dataset copy. An arbiter, option C, participates in replica-set voting and elections but deliberately does not maintain a copy of the database data. A shard, option D, is a data partition in a sharded cluster and is normally implemented as a replica set in production, but “shard” is not the replica-set member role that replicates the primary ' s data. Secondary behavior is central to MongoDB high availability, read-scaling options, backup strategies, and failover. Administrators monitor secondary replication lag and health to ensure the copies remain sufficiently current. Therefore the member responsible for maintaining copies of the primary ' s data is the secondary, making option A correct.

Study Guide reference/topic:Cluster Reliability and Data Resilience - replica-set primaries, secondaries, oplog replication, and redundancy.

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The outer $or returns a document if either branch is true. Document 1 satisfies the first branch because product equals " x-small box " , so it is included regardless of the second branch. The nested $and requires both qty != 50 and the absence of " brown " from the colors array. Document 2 has quantity 60 but contains " brown " , so it fails $nin. Document 3 has quantity 45 and its colors do not include brown, so it satisfies both conditions. Document 4 has no brown but quantity is exactly 50, so it fails $ne: 50. Document 5 has quantity 10 and colors [ ' grey ' , ' white ' ], so it also satisfies both nested predicates. The final set is therefore documents 1, 3, and 5. This question also illustrates that MongoDB applies an implicit AND between multiple top-level field predicates in the same document, but here the explicit $and makes the required conjunction clear. Option D is the only answer containing exactly the matching documents.

Study Guide reference/topic:MongoDB Architecture and Core Operations - logical query operators, $or, $and, $ne, and $nin.

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The $in query predicate matches a document when the queried field equals any value listed in the $in array. When the target field is itself an array, MongoDB compares the array elements against the values supplied to $in; one matching element is sufficient. Car 1 qualifies because its features array contains both " Leather Interior " and " 2WD " . Car 3 also qualifies because its array contains " Leather Interior " and " Auto Pilot " . Car 2 contains " Cloth Interior " , " Sun Roof " , and " XM Radio " , none of which are in the predicate array, so it is excluded. A common mistake is to read $in as requiring all values to be present. It does not: the semantics are an OR-style membership test. If the requirement were to ensure that several specified values were all present in an array, a different construct such as $all would be appropriate. Therefore, the result consists of the Toyota Celica and Tesla Model S documents only, making option A correct.

Study Guide reference/topic:MongoDB Architecture and Core Operations - querying documents, arrays, and the $in predicate.

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