The IS auditor's most important course of action after finding that several similar incidents were logged during the audit period is to determine if a root cause analysis was conducted. A root cause analysis is a systematic process that identifies the underlying causes of system failures or incidents. A root cause analysis can help to prevent recurrence of similar incidents, improve system performance and reliability, and enhance incident management processes. The IS auditor should evaluate whether a root cause analysis was performed for each incident, whether it was timely and thorough, and whether it resulted in effective corrective actions.

The best way to detect unauthorized copies of licensed software on systems is to conduct periodic software scanning. Software scanning is a process of using specialized tools or programs to scan the systems and identify the software installed, the license status, the usage, and the compliance with the software policies and agreements. Software scanning can help to detect any unauthorized, unlicensed, or illegal copies of software on the systems, as well as any discrepancies or violations of the software licenses. Software scanning can also help to optimize the software inventory, reduce the software costs, and improve the security and performance of the systems12.
Some examples of software scanning tools are:
* Microsoft Software Inventory Analyzer (MSIA): A free tool that scans Windows-based computers and servers and generates reports on the Microsoft products installed, such as operating systems, applications, and updates3.
* Belarc Advisor: A free tool that scans Windows-based computers and generates reports on the hardware and software installed, including license keys, versions, usage, and security status4.
* Lansweeper: A paid tool that scans Windows, Linux, Mac, and other network devices and generates reports on the hardware and software inventory, license compliance, configuration, and vulnerabilities5.
To conduct periodic software scanning, you need to:
* Choose a suitable software scanning tool that meets your needs and budget.
* Define the scope and frequency of the software scanning, such as which systems to scan, how often to scan, and what information to collect.
* Configure and run the software scanning tool according to the instructions and settings.
* Review and analyze the software scanning reports and identify any unauthorized copies of licensed software on the systems.
* Take appropriate actions to remove or regularize the unauthorized copies of licensed software on the systems.
* Document and report the results and findings of the software scanning.

Data analytics can be used to compare data from different sources and identify any discrepancies or anomalies. In this case, comparing a population of loans input in the origination system to loans booked on the servicing system can help detect any errors or frauds in the loan origination process. The other options are not examples of data analytics, but rather controls for data integrity, reconciliation, and error handling. References: CISA Review Manual (Digital Version), Chapter 3, Section 3.3.2

The best recommendation to prevent unauthorized access to a highly sensitive data center by piggybacking or tailgating is to use an airlock entrance. An airlock entrance is a type of access control system that consists of two doors that are interlocked, so that only one door can be opened at a time. This prevents an unauthorized person from following an authorized person into the data center without being detected. An airlock entrance can also be integrated with other security measures, such as biometrics, card readers, or PIN pads, to verify the identity and authorization of each person entering the data center.
Biometrics (option A) is a method of verifying the identity of a person based on their physical or behavioral characteristics, such as fingerprints, iris scans, or voice recognition. Biometrics can provide a high level of security, but they are not sufficient to prevent piggybacking or tailgating, as an unauthorized person can still follow an authorized person who has been authenticated by the biometric system.
Procedures for escorting visitors (option B) is a policy that requires all visitors to the data center to be accompanied by an authorized employee at all times. This can help prevent unauthorized access by visitors, but it does not address the risk of piggybacking or tailgating by other employees or contractors who may have legitimate access to the building but not to the data center.
Intruder alarms (option D) are devices that detect and alert when an unauthorized person enters a restricted area. Intruder alarms can provide a deterrent and a response mechanism for unauthorizedaccess, but they are not effective in preventing piggybacking or tailgating, as they rely on the detection of the intruder after they have already entered the data center.
References: 1: CISA Certification | Certified Information Systems Auditor | ISACA 2: CISA Certified Information Systems Auditor Study Guide, 4th Edition 3: CISA - Certified Information Systems Auditor Study Guide [Book]