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

The quantity condition is “less than or equal to 1000,” which maps to MongoDB ' s $lte comparison operator. The sales representative condition is “not equal to Anne,” which maps to $ne. When predicates on two different fields appear in the same query document, MongoDB applies an implicit logical AND, so both conditions must be true for a document to match. Option C therefore expresses exactly the requested filter: { quantity: { $lte: 1000 }, salesRep: { $ne: " Anne " } }. Options A and D use $neq, which is not MongoDB ' s inequality operator. Options B and D use $lt, which excludes documents whose quantity is exactly 1000 and therefore fails the “less than or equal” requirement. One nuance of $ne is that it can also match documents where the field is missing, because a missing field is not equal to the specified value. If the application requires salesRep to exist as well, an explicit existence predicate may be appropriate. For the wording shown, however, option C is the correct command.

Study Guide reference/topic:MongoDB Architecture and Core Operations - comparison predicates, $lte, $ne, and implicit AND semantics.

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MongoDB exposes server parameters that can be configured through the parameter framework. Among the choices, --setParameter is the option specifically designed to set a server parameter on the mongod command line, using syntax such as mongod --setParameter < name > = < value > . A configuration file can also contain a setParameter section, but --config by itself merely tells mongod which configuration file to load; it is not the parameter-setting mechanism identified by the question. Connection-string options control how clients connect and cannot be used to configure arbitrary server runtime parameters. Option D is also incorrect because the server must already be running for mongosh to issue administrative commands. A technical nuance is important: parameters that support modification while the process is already running are changed with the administrative setParameter command, for example db.adminCommand({setParameter:1, ...}). Such runtime changes may not persist across a restart unless the value is also configured for startup. Given the options provided and the exam wording, --setParameter is the intended method, so A is correct.

Study Guide reference/topic:MongoDB Architecture and Core Operations - server parameters, --setParameter, configuration files, and runtime administration.

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MongoDB supports direct equality matching against elements contained in an array. When the predicate is { sizes: " M " } and sizes is an array field, a document matches when at least one element of the array equals the scalar value " M " . Document 1 contains only " XS " and " S " , so it does not match. Document 2 contains " M " in [ ' S ' , ' M ' , ' XL ' ], and document 3 contains " M " in [ ' M ' , ' L ' , ' XL ' , ' XXL ' ]; both therefore match. No $elemMatch expression is required for this simple scalar membership test. $elemMatch becomes important when multiple conditions must be satisfied by the same array element, particularly for arrays of embedded documents or compound conditions. This array equality behavior is a core part of MongoDB ' s document query model and allows concise filtering of array-valued fields. The correct result is consequently the t-shirt and vest documents, which corresponds to option D. This same matching behavior applies consistently whenever a scalar predicate targets values stored inside a BSON array field.

Study Guide reference/topic:MongoDB Architecture and Core Operations - querying array fields and equality predicates.

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Encryption at rest protects persisted database data on storage media, but it is not a complete defense against every form of data exposure or breach. MongoDB ' s encrypted storage capabilities protect files and storage-level data, yet applications and the database server must still process authorized data in usable form. A compromised application account, stolen database credentials, excessive privileges, or a malicious authorized user can therefore expose data even when the underlying storage is encrypted. Network traffic also requires separate transport protection such as TLS; encryption at rest does not secure data as it travels between clients and servers. Option B incorrectly describes transport encryption rather than an at-rest capability. Option A is too subjective and not an inherent limitation, particularly in managed deployments where storage encryption may be enabled automatically. Option D is similarly overstated; encryption adds cryptographic work, but severe performance impact is not an intrinsic defining limitation. The correct security model is defense in depth: combine at-rest encryption with TLS, strong authentication, least-privilege authorization, auditing, and secure key management. Among the choices, C best captures the limitation that at-rest encryption alone cannot prevent all data breaches.

Study Guide reference/topic:Security, Networking, and Encryption - encryption at rest, TLS, authorization, and defense in depth.

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