The primary purpose of performing a parallel run of a new system is to validate the new system against its predecessor. A parallel run is a strategy for system changeover where a new system slowly assumes the roles of the older system while both systems operate simultaneously. This allows for comparison of the results and outputs of both systems to ensure that the new system is working correctly and reliably. A parallel run can also help identify and resolve any errors, discrepancies, or inconsistencies in the new system before the old system is discontinued.
The other options are not the primary purpose of performing a parallel run of a new system. A. To train the end users and supporting staff on the new system. Training is an important part of system implementation, but it is not the main reason for doing a parallel run. Training can be done before, during, or after the parallel run, depending on the needs and preferences of the organization. B. To verify the new system provides required business functionality. Verifying the business functionality of the new system is part of user acceptance testing (UAT), which is a formal and structured process of testing whether the new system meets the specifications and expectations of the users and stakeholders. UAT is usually done before the parallel run, as a prerequisite for system changeover. C. To reduce the need for additional testing. Reducing the need for additional testing is not the primary purpose of performing a parallel run, but rather a possible benefit or outcome of doing so. A parallel run can help ensure that the new system is thoroughly tested and validated in a real-world environment, which may reduce the likelihood of encountering major issues or defects later on.
However, additional testing may still be needed after the parallel run, depending on the feedback and evaluation of the users and stakeholders.
References:
* ISACA, CISA Review Manual, 27th Edition, 2019, p. 2471
* IS

The first thing that an IS auditor should review when finding that transaction processing times in an order processing system have significantly increased after a major release is stress testing results. Stress testing is a type of testing that evaluates how a system performs under extreme or abnormal conditions, such as high volume, load, or concurrency of transactions. Stress testing results can help explain why transaction processing times in an order processing system have significantly increased after a major release by revealing any bottlenecks, limitations, or errors in the system's capacity, performance, or functionality under stress. The other options are not as relevant as stress testing results in explaining why transaction processing times in an order processing system have significantly increased after a major release, as they do not directly measure how the system performs under extreme or abnormal conditions. Capacity management plan is a document that defines and implements the processes and activities for ensuring that the system has adequate resources and capabilities to meet current and future demands. Training plans are documents that define and implement the processes and activities for ensuring that the system users have adequate skills and knowledge to use the system effectively and efficiently. Database conversion results are outcomes or outputs of transforming data from one format or structure to another to suit the system's requirements or specifications. References: CISA Review Manual (Digital Version), Chapter 3, Section 3.3

Audit planning is the process of developing an overall strategy and approach for conducting an audit. Audit planning involves identifying the objectives, scope, criteria, and methodology of the audit, as well as the resources, schedule, and reporting requirements. Audit planning also involves performing a risk assessment to identify and prioritize the areas of highest risk and significance for the audit1.
Risk assessment is a systematic process of evaluating the potential risks that may be involved in a projected activity or undertaking. Risk assessment involves identifying the sources and causes of risk, analyzing the likelihood and impact of risk, and determining the level of risk and the appropriate response2.
During audit planning, the IS audit manager is considering whether to budget for audits of entities regarded by the business as having low risk. The best course of action in this situation is C. Validate the low-risk entity ratings and apply professional judgment.
This is because validating the low-risk entity ratings can help to ensure that the risk assessment is accurate, reliable, and consistent with the business objectives and expectations. Validating the low-risk entity ratings can also help to identify any changes or developments that may affect the risk profile of the entities since the last assessment. Applying professional judgment can help to determine whether the low-risk entities should be included or excluded from the audit plan, based on factors such as materiality, relevance, significance, and assurance needs3.

The best way to determine whether unauthorized changes have been made to production programs is to use source code comparison software to compare the current version of the programs with the previous version or the approved version. This will identify any changes that have been made without proper authorization or documentation. Tracing PCRs to logs or vice versa will only verify that the authorized changes have been recorded, but not detect any unauthorized changes. References: Standards, Guidelines, Tools and Techniques
- ISACA, section "IS Audit and Assurance Tools and Techniques"