CompTIA Security_ Deluxe Study Guide_ SY0-201 - Emmett Dulaney [150]
As simple as it sounds, such things happen all the time. When they do, you need to be ready with backups—backup tapes, backup servers, backup monitors, and so on.
Major fluctuations in AC power can contribute to a condition known as chip creep. With creep, unsoldered chips slowly work their way loose and out of a socket over time.
The following products solve most electrical line problems:
Surge protectors Surge protectors protect electrical components from momentary or instantaneous increases (called spikes) in a power line. Most surge protectors shunt a voltage spike to ground through the use of small devices called metal oxide varistors (MOVs). Large-scale surge protectors are usually found in building power supplies or at power-feed points in the building. Portable surge protectors can be purchased as part of an extension cord or power strip. If subsequent surges occur, the surge protector may not prevent them from being passed through the line to the computer system. Surge protectors are passive devices, and they accomplish no purpose until a surge occurs.
Power conditioners Power conditioners are active devices that effectively isolate and regulate voltage in a building. They monitor the power in the building and clean it up. Power conditioners usually include filters, surge suppressors, and temporary voltage regulation. They can also activate backup power supplies. Power conditioners can be part of the overall building power scheme; it’s also common to see them dedicated strictly to computer rooms.
Backup power Backup power is generally used in situations where continuous power is needed in the event of a power loss. These types of systems are usually designed for either short-term, as in the case of a battery backup system, or long-term uses, as in an uninterruptible power supply (UPS). UPS systems generally use batteries to provide short-term power. Longer-term backup power comes from power generators that frequently have their own power-loss-sensing circuitry. Power generators kick in if a power loss is detected, and they provide power until disabled. The generators require a short amount of time to start providing power, and the battery backup systems provide time for the generators to come online. Most generator systems don’t automatically turn off when power is restored to a building—they’re turned off manually. This is necessary because it’s common for several false starts to occur before power is restored from the power grid.
Most power generators are either gas or diesel operated, and they require preventive maintenance on a regular basis. These systems aren’t much use if they don’t start when needed or they fail because no oil is in the motor. Newer systems are becoming available that are based on fuel cell technology; they will probably be very reliable and require less maintenance.
Shielding
Shielding refers to the process of preventing electronic emissions from your computer systems from being used to gather intelligence and to preventing outside electronic emissions from disrupting your information-processing abilities. In a fixed facility, such as a computer center, surrounding the computer room with a Faraday cage can provide electronic shielding. A Faraday cage usually consists of an electrically conductive wire mesh or other conductor woven into a “cage” that surrounds a room. The conductor is then grounded. Because of this cage, few electromagnetic signals can either enter or leave the room, thereby reducing the ability to eavesdrop on a computer conversation. In order to verify the functionality of the cage, radio frequency (RF) emissions from the room are tested with special measuring devices.
The following section discusses the problems of electromagnetic and radio frequency interference.
Electromagnetic Interference and Radio Frequency Interference
Electromagnetic interference