50. d. Many physical problems in local-area networks (LANs) are related to cables because they can be broken or twisted. Servers can be physically damaged due to disk head crash or power irregularities such as over or under voltage conditions. An uninterruptible power supply provides power redundancy and protection to servers and workstations. Servers can be disk duplexed for redundancy. Redundant topologies such as star, mesh, or ring can provide a duplicate path should a main cable link fail. Hubs require physical controls such as lock and key because they are stored in wiring closets; although, they can also benefit from redundancy, which can be expensive. Given the choices, it is preferable to have redundant facilities for cables, servers, and power supplies.
51. System reliability controls for hardware include which of the following?
a. Mechanisms to decrease mean time to repair and to increase mean time between failures
b. Redundant computer hardware
c. Backup computer facilities
d. Contingency plans
51. a. Mean time to repair (MTTR) is the amount of time it takes to resume normal operation. It is expressed in minutes or hours taken to repair computer equipment. The smaller the MTTR for hardware, the more reliable it is. Mean time between failures (MTBF) is the average length of time the hardware is functional. MTBF is expressed as the average number of hours or days between failures. The larger the MTBF for hardware, the more reliable it is.
Redundant computer hardware and backup computer facilities are incorrect because they are examples of system availability controls. They also address contingencies in case of a computer disaster.
52. Fail-soft control is an example of which of the following?
a. Continuity controls
b. Accuracy controls
c. Completeness controls
d. Consistency controls
52. a. As a part of the preventive control category, fail-soft is a continuity control. It is the selective termination of affected nonessential processing when a hardware or software failure is detected in a computer system. A computer system continues to function because of its resilience.
Accuracy controls are incorrect because they include data editing and validation routines. Completeness controls are incorrect because they look for the presence of all the required values or elements. Consistency controls are incorrect because they ensure repeatability of certain transactions with the same attributes.
53. Information availability controls do not include which of the following?
a. Backup and recovery
b. Storage media
c. Physical and logical security
d. Alternative computer equipment and facilities
53. b. Storage media has nothing to do with information availability. Data will be stored somewhere on some media. It is not a decision criterion. Management’s goal is to gather useful information and to make it available to authorized users. System backup and recovery procedures and alternative computer equipment and facilities help ensure that the recovery is as timely as possible. Both physical and logical access controls become important. System failures and other interruptions are common.
54. From an operations viewpoint, the first step in contingency planning is to perform a(n):
a. Operating systems software backup
b. Applications software backup
c. Documentation backup
d. Hardware backup
54. d. Hardware backup is the first step in contingency planning. All computer installations must include formal arrangements for alternative processing capability in the event their data center or any portion of the work environment becomes disabled. These plans can take several forms and involve the use of another data center. In addition, hardware manufacturers and software vendors can be helpful in locating an alternative processing site and in some cases provide backup equipment under emergency conditions. The more common plans are service bureaus, reciprocal arrangements, and hot sites.
After hardware is backed up, operating systems software is backed up next, followed by applications software backup and documentation.
55. The primary contingency strategy for application systems and data is regular backup and secure offsite storage. From an operations viewpoint, which of the following decisions is least important to address?
a. How often is the backup performed?
b. How often is the backup stored offsite?
c. How often is the backup used?
d. How often is the backup transported?
