John, a disgruntled ex-employee of an organization, contacted a professional hacker to exploit the organization. In the attack process, the professional hacker installed a scanner on a machine belongi

An agent-based scanner involves installing scanning software (an agent) directly onto a host machine within the network. In this scenario, the hacker installed the scanner on a victim's machine, allowing it to operate from within the network perimeter to identify vulnerabilities on other networked systems - this inside-out scanning approach is the hallmark of agent-based vulnerability assessment tools.

A network-based scanner operates remotely from a central location over the network to probe target systems, and is not installed directly on a victim's machine within the target environment.

A cluster scanner is not a standard classification of vulnerability assessment tool in this context; it does not describe the method of installing a scanner on a compromised internal host.

A proxy scanner routes scanning traffic through a proxy server to assess vulnerabilities, which is a different architecture from installing a scanner agent directly on a victim's machine.