The best action for the administrator to take is to delete all the backup files that are not required by the backup retention policy. This will free up disk space on the server and also comply with the best practices for data backup and recovery. The backup retention policy defines how long the backup files should be kept and when they should be deleted or archived. The other options are either risky, inefficient, or impractical. For example, moving all the backup files to external disks would require additional hardware and time, deleting all the backup files containing data that is rated as classified would compromise data security and compliance, and deleting all the backup files except for the most recent one would limit the recovery options in case of a disaster. Reference: CompTIA DataSys+ Course Outline, Domain 5.0 Business Continuity, Objective 5.2 Given a scenario, implement backup and restoration of database management systems.

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 property that addresses this concern is durability. Durability is one of the four properties (ACID) that ensure reliable transactions in a database system. Durability means that once a transaction has been committed, its effects are permanent and will not be lost in case of system failure, power outage, crash, etc. Durability can be achieved by using techniques such as write-ahead logging, checkpoints, backup and recovery, etc. The other options are either not related or not specific to this concern. For example, isolation means that concurrent transactions do not interfere with each other and produce consistent results; atomicity means that a transaction is either executed as a whole or not at all; consistency means that a transaction preserves the validity and integrity of the data. Reference: CompTIA DataSys+ Course Outline, Domain 1.0 Database Fundamentals, Objective 1.3 Given a scenario, identify common database issues.

The best way for the administrator to accomplish this task is to create a materialized view. A materialized view is a type of view that stores the result of a query on one or more tables as a separate table in the database. A materialized view can aggregate data from multiple tables in a way that does not impact the original tables, and then provide this information to a department as a single source of truth. A materialized view also improves query performance and efficiency by reducing the need to recompute complex queries every time they are executed. The other options are either not suitable or not optimal for this task. For example, creating indexes on those tables may improve query performance on individual tables, but not on aggregated data; creating a new database may require additional resources and maintenance, and may introduce inconsistency or redundancy; creating a function may require additional coding and execution, and may not store the result as a separate table. Reference: CompTIA DataSys+ Course Outline, Domain 2.0 Database Deployment, Objective 2.2 Given a scenario, create database objects using scripting and programming languages.

The document that a company should develop to ensure preparedness for a fire in a data center is a disaster recovery plan. A disaster recovery plan is a document that outlines how an organization will continue its operations in the event of a disaster or disruption, such as fire, flood, earthquake, cyberattack, etc. A disaster recovery plan typically includes the following elements: - The objectives and scope of the plan - The roles and responsibilities of the staff involved - The identification and assessment of the risks and impacts - The strategies and procedures for restoring the critical functions and data - The resources and tools required for the recovery process - The testing and maintenance schedule for the plan A disaster recovery plan helps an organization to minimize the damage and downtime caused by a disaster, as well as to resume normal operations as soon as possible. The other options are either different types of documents or not specific to fire preparedness. For example, a deployment plan is a document that describes how a system or software will be installed or launched; a backup plan is a document that specifies how data will be copied and stored for backup purposes; a data retention policy is a document that defines how long data should be kept and when it should be deleted or archived. Reference: CompTIA DataSys+ Course Outline, Domain 5.0 Business Continuity, Objective 5.4 Given a scenario, implement disaster recovery methods.