The best way to ensure that business continuity plans (BCPs) will work effectively in the event of a major disaster is to involve staff at all levels in periodic paper walk-through exercises. This means that the BCPs are tested and validated by the people who will execute them in a real situation, and any gaps, errors, or inconsistencies can be identified and corrected. Paper walk-through exercises are also a good way to raise awareness and train staff on their roles and responsibilities in a BCP scenario, as well as to evaluate the feasibility and effectiveness of the recovery strategies1.
The other options are not the best ways to ensure that BCPs will work effectively, because they do not involve testing or validating the plans. Preparing detailed plans for each business function is important, but it does not guarantee that the plans are realistic, practical, or aligned with the overall business objectives and priorities2. Regularly updating business impact assessments is also essential, but it does not ensure that the BCPs are aligned with the current business environment and risks2. Making senior managers responsible for their plan sections is a good way to assign accountability and authority, but it does not ensure that the plansections are coordinated and integrated with each other2. References:
* Best Practice Guide: Business Continuity Planning (BCP)3
* Best Practices for Creating a Business Continuity Plan1
* Business Continuity Plan Best Practices

The main purpose of an IDS is to detect and report malicious or suspicious activity on a network or a host. If an IDS fails to identify actual attacks, it means that the IDS is not functioning properly or effectively, and it exposes the organization to serious security risks and potential damage. This is the most concerning scenario for an IS auditor, as it indicates a major deficiency in the IDS performance and configuration.
ReferencesWhat is an intrusion detection system (IDS)?What is Intrusion Detection Systems (IDS)? How does it Work?When reviewing an intrusion detection system (IDS), an IS auditor ...Intrusion Detection Systems (IDS)-An Overview with a Generalized ...An overview of issues in testing intrusion detection systems - NISTA Review of Intrusion Detection Systems and Their ...