A rollback is a Transaction Control Language (TCL) command used to undo changes made during a transaction, ensuring database integrity by reverting to a previous stable state.

The cloud delivery model that provides users with the highest level of flexibility regarding resource provisioning and administration is IaaS. IaaS, or Infrastructure as a Service, is a cloud delivery model that provides users with access to virtualized computing resources, such as servers, storage, network, and operating systems, over the internet. Users can provision, configure, and manage these resources according to their needs and preferences, without having to worry about the maintenance or security of the physical infrastructure. IaaS offers users the most control and customization over their cloud environment, as well as the ability to scale up or down as needed. The other options are either different cloud delivery models or not related to cloud computing at all. For example, DBaaS, or Database as a Service, is a cloud delivery model that provides users with access to database management systems and tools over the internet; SaaS, or Software as a Service, is a cloud delivery model that provides users with access to software applications and services over the internet; PaaS, or Platform as a Service, is a cloud delivery model that provides users with access to development platforms and tools over the internet.

Impacts describe the actual damage or disruption caused by attacks like SQL injection and denial-of-service, reflecting their effect on systems and data.

The two resources that are best for monitoring potential server issues are CPU usage and memory usage. CPU usage is the percentage of time that the processor (CPU) of the server is busy executing instructions or processes. CPU usage indicates how much workload the server can handle and how fast it can process requests. High CPU usage may affect the performance or availability of the server and cause delays or errors. Memory usage is the amount of physical memory (RAM) or virtual memory (swap space) that the server uses to store data or run applications. Memory usage indicates how much space the server has to store temporary or intermediate data or results. High memory usage may affect the performance or availability of the server and cause swapping or paging. The other options are either not relevant or not direct indicators of server health. For example, user connections are the number of users who are connected to a database server at any given time; firewall usage is the amount of data that passes through a firewall device or software; index usage is the frequency or efficiency of using indexes on tables to speed up queries; query execution is the process of running SQL statements on a database server.