Configuring each authentication server as belonging to a cluster of authentication servers is the best way to minimize performance degradation of servers used to authenticate users of an e-commerce website. A cluster is a group of servers that work together to provide high availability, load balancing, and fault tolerance. If one server fails or becomes overloaded, another server in the cluster can take over its workload without disrupting the service. A single server as a primary authentication server and a second server as a secondary authentication server is not as effective as a cluster, because the secondary server is only used when the primary server fails, which means it is idle most of the time and does not improve performance. Configuring each authentication server and ensuring that each disk of its RAID is attached to the primary controller does not address the issue of performance degradation, but rather the issue of data redundancy and reliability.
RAID (redundant array of independent disks) is a technology that combines multiple disks into a logical unit that can tolerate disk failures and improve data access speed. Configuring each authentication server and ensuring that the disks of each server form part of a duplex does not address the issue of performance degradation, but rather the issue of data backup and recovery. A duplex is a pair of disks that store identical copies of data, so that if one disk fails, the other disk can be used to restore the data. References: ISACA CISA Review Manual 27th Edition, page 310

The best phase of the software development life cycle to initiate the discussion of application controls is the application design phase when process functionalities are finalized. Application controls are the policies, procedures, and techniques that ensure the completeness, accuracy, validity, and authorization of data input, processing, output, and storage in an application. Application controls help prevent, detect, or correct errors and fraud in software applications. Examples of application controls include input validation, edit checks, reconciliation, encryption, access control, audit trails, etc.
The application design phase is when the software requirements are translated into a logical and physical design that specifies how the application will look and work. This phase is the best time to discuss application controls because it allows the developers to incorporate them into the design specifications and ensure that they are aligned with the business objectives and user needs. By discussing application controls early in the design phase, the developers can also avoid costly rework or changes later in the development process.
The other phases are not as optimal as the application design phase to initiate the discussion of application controls. A. Business case development phase when stakeholders are identified. The business case development phase is when the feasibility, scope, objectives, benefits, risks, and costs of a software project are defined and evaluated. This phase is important for obtaining stakeholder approval and support for the project, but it is too early to discuss application controls in detail because the software requirements and functionalities are not yet clear or finalized. B. User acceptance testing (UAT) phase when test scenarios are designed. The user acceptance testing phase is when the software is tested by the end-users or stakeholders to verify that it meets their expectations and requirements. This phase is too late to discuss application controls because it is near the end of the development process and any changes or additions to the application controls would require retesting and revalidation of the software. C. Application coding phase when algorithms are developed to solve business problems. The application coding phase is when the software design is translated into executable code using programming languages and tools. This phase is not ideal to discuss application controls because it is after the design phase and any changes or additions to the application controls would require redesigning and recoding of the software.
References:
ISACA, CISA Review Manual, 27th Edition, 2019, p. 2471
ISACA, CISA Review Questions, Answers and Explanations Database - 12 Month Subscription2 What Is Application Control? | McAfee3 What Is Application Lifecycle Management? | Red Hat4

A system electronic log is the most useful source of information for an IS auditor to review all access attempts to a video-monitored and proximity card-controlled communications room. A system electronic log can provide accurate and detailed records of the date, time, card number, and status (success or failure) of each access attempt. A system electronic log can also be easily searched, filtered, and analyzed by the auditor to identify any unauthorized or suspicious access attempts.
A manual sign-in and sign-out log is not as reliable or useful as a system electronic log, because it depends on the honesty and compliance of the users. A manual log can be easily manipulated, forged, or omitted by the users or intruders. A manual log also does not capture the status of each access attempt, and it can be difficult to verify the identity of the users based on their signatures.
An alarm system with CCTV is not as useful as a system electronic log, because it only captures the events that trigger the alarm, such as unauthorized or forced entry. An alarm system with CCTV does not provide a complete record of all access attempts, and it can be affected by factors such as camera angle, lighting, and resolution. An alarm system with CCTV also requires more time and effort to review the video footage by the auditor.
A security incident log is not as useful as a system electronic log, because it only records the incidents that are reported by the users or detected by the security staff. A security incident log does not provide a comprehensive record of all access attempts, and it can be incomplete or inaccurate depending on the reporting and detection mechanisms. A security incident log also does not capture the details of each access attempt, such as the card number and status.
References:
* ISACA CISA Review Manual 27th Edition (2019), page 247
* ISACA CISA Certified Information Systems Auditor Exam ... - PUPUWEB

Enterprise Architecture (EA) documentation primarily includes strategic and operational blueprints outlining the evolution of IT infrastructure to align with business goals.Roadmaps showing the evolution from current state to future state (C)are essential for understanding how the organization's IT environment will change over time to support business strategy.
Other options:
Contact information for key resources (A)is more of an operational or administrative document rather than an EA component.
Detailed encryption standards (B)would typically be found in security policies or system-specific documentation rather than in EA documentation.
Protocols used to communicate between systems (D)are typically documented within network or system architecture diagrams rather than high-level EA documentation.
Reference:ISACA CISA Review Manual, IT Governance and Management of IT

The most important part of a feasibility study is the economics1. A cost-benefit analysis of available products is crucial as it helps to understand the economic viability of the project1. It compares the costs of the project with the benefits it is expected to deliver, which is essential for making informed decisions1. Omitting this could lead to investments in hardware that may not provide the expected returns or meet the organization's needs.
References:
* The Components of a Feasibility Study - ProjectEngineer