83. a. Disk concatenation is a logical joining of two series of data or disks. In data concatenation, two or more data elements or data files are often concatenated to provide a unique name or reference. In disk concatenation, several disk address spaces are concatenated to present a single larger address spaces.
The other three choices are incorrect. Disk striping has more than one disk and more than one partition, and is same as disk arrays. Disk mirroring occurs when a file server contains two physical disks and one channel, and all information is written to both disks simultaneously. Disk replication occurs when data is written to two different disks to ensure that two valid copies of the data are always available.
84. All the following are needed for a timely and emergency maintenance work to reduce the risk to an organization except:
a. Maintenance vendor service-level agreement
b. Spare parts inventory
c. Help-desk staff
d. Commercial courier delivery service agreement
84. c. Information system components, when not operational, can result in increased risk to organizations because the security functionality intended by that component is not being provided. Examples of security-critical components include firewalls, hardware/software guards, gateways, intrusion detection and prevention systems, audit repositories, and authentication servers. The organizations need to have a maintenance vendor service-level agreement, stock spare parts inventory, and a delivery service agreement with a commercial transportation courier to deliver the required parts on time to reduce the risk of running out of components and parts.
Help-desk staff, whether they are internal or external, are not needed for all types of maintenance work, whether it is scheduled or unscheduled, or whether it is normal or emergency. Their job is to help system users on routine matters (problems and issues) and escalate them to the right party when they cannot resolve these matters.
85. Which of the following is the basis for ensuring software reliability?
a. Testing
b. Debugging
c. Design
d. Programming
85. c. The basis for software reliability is design, not testing, debugging, or programming. For example, using the top-down design and development techniques and employing modular design principles, software can be made more reliable than otherwise. Reliability is the degree of confidence that a system will successfully function in a certain environment during a specified time period.
Testing is incorrect because its purpose is to validate that the software meets its stated requirements. Debugging is incorrect because its purpose is to detect, locate, and correct faults in a computer program. Programming is incorrect because its purpose is to convert the design specifications into program instructions that the computer can understand.
86. In software configuration management, changes to software should be subjected to which of the following types of testing prior to software release and distribution?
a. Black-box testing
b. Regression testing
c. White-box testing
d. Gray-box testing
86. b. Regression testing is a method to ensure that changes to one part of the software system do not adversely impact other parts. The other three choices do not have such capabilities. Black-box testing is a functional analysis of a system, and known as generalized testing. White-box testing is a structural analysis of a system, and known as detailed testing or logic testing. Gray-box testing assumes some knowledge of the internal structures and implementation details of the assessment object, and known as focused testing.
87. Which of the following software quality characteristics is difficult to define and test?
a. Functionality
b. Reliability
c. Usability
d. Efficiency
87. c. Usability is a set of attributes that bear on the effort needed for use, and on the individual assessment of such use, by a stated or implied set of users. In a way, usability means understandability and ease of use. Because of its subjective nature, varying from person to person, it is hard to define and test.
