Internal firewalls are highly effective for isolating Internet of Things (IoT) devices from corporate network traffic. By segmenting the network and restricting communication between devices and the main corporate infrastructure, internal firewalls help mitigate the risk of lateral movement and data breaches caused by compromised IoT devices.
* Blockchain Technology (Option B):This is useful for ensuring data integrity but not for network isolation.
* Content Filtering Proxy (Option C):This is designed to manage web traffic and does not provide network segmentation.
* Zero Trust Architecture (Option D):While Zero Trust provides robust access controls, internal firewalls are more directly suited for traffic isolation.
Reference:ISACA CISA Review Manual, Job Practice Area 4: Protection of Information Assets.

The scanning will not degrade system performance. This is the most important consideration when establishing vulnerability scanning on critical IT infrastructure, because any degradation of system performance could affect the availability, reliability, and functionality of the IT services that depend on the infrastructure. Scanning during non-peak hours (A) could reduce the impact of scanning on system performance, but it does not guarantee that the scanning will not cause any degradation. Scanning followed by penetration testing (B) could provide more in-depth information about the vulnerabilities and their exploitability, but it does not address the potential impact of scanning on system performance. Scanning cost- effectiveness is a relevant factor for choosing a scanning service or tool, but it is not as important as ensuring that the scanning will not compromise the system performance.
Reference: CISA Vulnerability Scanning, Description.

The auditor should be most concerned about the security policy documents being available on a public domain website. This is because this exposes the organization's security posture and strategy to potential attackers, who can exploit the information to launch targeted attacks or bypass the security controls. The security policy documents should be classified as confidential and protected from unauthorized access or disclosure. The other options are less severe than exposing the security policy documents to the public, although they may also indicate some gaps or weaknesses in the security policy development, implementation, or maintenance process. References:
* CISA Review Manual (Digital Version), Chapter 5, Section 5.31
* CISA Online Review Course, Domain 3, Module 1, Lesson 12

When auditing the closing stages of a system development project, the most important consideration should be the user acceptance test (UAT) results. The UAT is a critical phase of the system development life cycle (SDLC) that ensures that the system meets the functional requirements and expectations of the end users. The UAT results provide evidence of the system's quality, performance, usability, and reliability. Control requirements, rollback procedures, and functional requirements documentation are also important considerations, but they are not ascrucial as the UAT results in determining if the system is ready for deployment. References: CISA Review Manual (Digital Version)1, page 325.