The most likely causes of the reporting application not working are that the access permissions for the service account used by the reporting application were not changed, and that the reporting application's mapping to the database location was not updated. These two factors could prevent the reporting application from accessing the new database server. The other options are either irrelevant or unlikely to cause the problem. Reference: CompTIA DataSys+ Course Outline, Domain 3.0 Database Management and Maintenance, Objective 3.2 Given a scenario, troubleshoot common database issues.

The NF (normal form) that is considered the most preferable for relational database design is 3 NF. 3 NF, or Third Normal Form, is a level of normalization that organizes data into tables and columns to reduce redundancy and improve consistency. Normalization is a process that applies a set of rules or criteria to eliminate or minimize the anomalies or problems that may arise from inserting, updating, or deleting data in a database. 3 NF is achieved when a table satisfies the following conditions: - It is in 2 NF (Second Normal Form), which means that every non-key column depends on the whole primary key and not on any subset of it - It has no transitive dependencies, which means that every non-key column depends directly on the primary key and not on any other non-key column 3 NF is considered the most preferable for relational database design because it ensures that each table has only one purpose or theme and that each column has only one value or meaning. This helps avoid data duplication, inconsistency, and update anomalies. The other options are either lower or higher levels of normalization that are either less preferable or less practical for relational database design. For example, 1 NF (First Normal Form) is the lowest level of normalization that requires each column to have atomic values and each row to have a unique identifier; 4 NF (Fourth Normal Form) is a higher level of normalization that requires each table to have no multi-valued dependencies, which means that there are no columns that can have more than one value for the same primary key value; 2 NF (Second Normal Form) is an intermediate level of normalization that requires each non-key column to depend on the whole primary key and not on any subset of it. Reference: CompTIA DataSys+ Course Outline, Domain 1.0 Database Fundamentals, Objective 1.2 Given a scenario, execute database tasks using scripting and programming languages.

The NoSQL database type that best categorizes MongoDB is document. Document databases are databases that store and manage data as documents, which are collections of fields and values in formats such as JSON (JavaScript Object Notation) or XML (Extensible Markup Language). Document databases do not use any schema or structure to organize data, but rather use identifiers or indexes to enable flexible and dynamic access to data based on fields or values. Document databases are suitable for storing large amounts of complex or unstructured data that have variable attributes or nested structures. MongoDB is an example of a document database that uses JSON-like documents to store and query data. The other options are either different types of NoSQL databases or not related to NoSQL databases at all. For example, column-oriented databases are databases that store and manage data as columns rather than rows; graph databases are databases that store and manage data as nodes and edges that represent entities and relationships; key-value stores are databases that store and manage data as pairs of keys and values. Reference: CompTIA DataSys+ Course Outline, Domain 1.0 Database Fundamentals, Objective 1.1 Given a scenario, identify common database types.

The option that sets the age requirement for data that should be recovered after a major disaster is RPO. RPO, or Recovery Point Objective, is a metric that defines the maximum amount of data that can be lost or acceptable data loss in the event of a disaster or disruption. RPO indicates how frequently the data should be backed up or replicated to minimize the risk of data loss. RPO also sets the age requirement for data that should be recovered after a major disaster, as it determines how far back in time the recovery process should go. For example, if the RPO is one hour, then the data should be backed up or replicated every hour, and the recovery process should restore the data to the state it was in one hour before the disaster. The other options are either different metrics or not related to data recovery at all. For example, MTBF, or Mean Time Between Failures, is a metric that measures the average time that a system or component operates without failure; RTO, or Recovery Time Objective, is a metric that defines the maximum amount of time that can be taken to restore a system or service after a disaster or disruption; MTTF, or Mean Time To Failure, is a metric that measures the average time that a system or component operates until it fails. Reference: CompTIA DataSys+ Course Outline, Domain 5.0 Business Continuity, Objective 5.3 Given a scenario, implement backup and restoration of data.

The instruction that is found on a Linux command-line script and represents a system shell is #!/bin/bash. This instruction is called a shebang or a hashbang, and it indicates the interpreter that should be used to execute the script. In this case, the interpreter is /bin/bash, which is the path to the bash shell, a common system shell for Linux. A system shell is a program that provides an interface for users to interact with the operating system, either through commands or scripts. A system shell can also perform various tasks, such as file management, process control, variable assignment, etc. The other options are either incorrect or not typical for this purpose. For example, /bin/bash is the path to the bash shell, but it does not indicate the interpreter for the script; #/bin/shell is not a valid shebang or a path to a system shell; >/bin/sh is a redirection operator followed by a path to a system shell, but it does not indicate the interpreter for the script. Reference: CompTIA DataSys+ Course Outline, Domain 2.0 Database Deployment, Objective 2.2 Given a scenario, create database objects using scripting and programming languages.