Explanation
HIDS (Host-based Intrusion Detection System) is the tool that will provide the administrator with the most information about potential attacks on a cloud IaaS instance. HIDS is a software or agent that monitors and analyzes the activities and events on a host system or device, such as a cloud instance. HIDS can detect and alert on any malicious or anomalous behavior, such as unauthorized access, malware infection, configuration changes, etc., that may indicate an attack or compromise.

Reference:
https://www.softwaretestinghelp.com/regression-testing-tools-and-methods/

Explanation
The technology that provides the most portability for a multicloud environment is containers. Containers are units of software that package an application and its dependencies into a standardized and isolated environment that can run on any platform or cloud service. Containers are lightweight, scalable, and portable, as they do not depend on the underlying infrastructure or operating system. Containers can also be managed by orchestration tools that automate the deployment, scaling, and networking of containerized applications across multiple clouds. Reference: [CompTIA Cloud+ Certification Exam Objectives], Domain 1.0 Configuration and Deployment, Objective 1.3 Given a scenario involving integration between multiple cloud environments, select an appropriate solution design.

Reference:
https://www.fsl.cs.sunysb.edu/docs/integrity-storagess05/integrity.html

Database replication is the best technique to migrate databases from an on-premises IaaS-hosted environment to a public DBaaS solution. Database replication is a process of copying data from one database server to another database server in real-time or near real-time. Database replication can ensure data consistency and availability across different locations and platforms. Database replication can facilitate migration by synchronizing data between on-premises databases and cloud databases.