Free CDCP Questions Attempt

Availability is the degree to which a system, product or component is operational and accessible when required for use. It is one of the attributes of reliability, which is the ability of a system or component to perform its required functions under stated conditions for a specified period of time. Availability can be calculated as the ratio of the expected value of the uptime (the time when the system is functional) to the total time (uptime plus downtime) of a system or component. Availability can also be influenced by factors such as maintainability, fault tolerance, redundancy, diagnostics, and logistics.

References: EPI Data Centre Professional (CDCP®) Preparation Guide, page 8; Availability - Wikipedia; Reliability - ISO 25000.

Optical fiber cables are composed of a core, a cladding, and a coating. The core is the central part of the fiber that carries the light signal. The cladding is the layer surrounding the core that reflects the light back into the core and prevents signal loss. The coating is the protective layer that covers the cladding and provides mechanical strength and environmental protection. The specifications of an optical fiber cable indicate the dimensions of the core and the cladding in microns (μm), which are one millionth of a meter. For example, a 50/125 μm cable has a core diameter of 50 μm and a cladding diameter of 125 μm. The coating diameter is usually 250 μm, but it is not part of the specifications.

References: Multimode Optical Fiber Selection & Specification - Corning, Optical Fiber OM3 (50/125µm Multimode Fiber), 50/125 Graded-Index OM2 Optical Fiber - OFS

Class D fires involve combustible metals or combustible metal alloys such as magnesium, sodium and potassium. These metals can react violently with water, air, or other chemicals, and require special extinguishing agents1

References: 1: EPI Data Centre Professional (CDCP®) Reference Materials, page 16.

The four main components of a refrigeration circuit are the evaporator, the compressor, the condenser, and the expansion valve, according to the CDCP Preparation Guide1 and various web sources234. A refrigeration circuit is a system that transfers heat from a low-temperature region to a high-temperature region, using a working fluid called refrigerant. The refrigeration circuit operates in a closed loop, where the refrigerant changes its state from liquid to vapor and back to liquid, while absorbing and releasing heat. The four main components of the refrigeration circuit perform the following functions:

•The evaporator is a heat exchanger that absorbs heat from the low-temperature region, such as the data centre room, and transfers it to the refrigerant. The refrigerant enters the evaporator as a low-pressure, low-temperature liquid, and leaves the evaporator as a low-pressure, low-temperature vapor.

•The compressor is a mechanical device that increases the pressure and temperature of the refrigerant vapor. The refrigerant enters the compressor as a low-pressure, low-temperature vapor, and leaves the compressor as a high-pressure, high-temperature vapor.

•The condenser is another heat exchanger that releases heat from the refrigerant to the high-temperature region, such as the outside air or water. The refrigerant enters the condenser as a high-pressure, high-temperature vapor, and leaves the condenser as a high-pressure, low-temperature liquid.

•The expansion valve is a device that reduces the pressure and temperature of the refrigerant liquid. The refrigerant enters the expansion valve as a high-pressure, low-temperature liquid, and leaves the expansion valve as a low-pressure, low-temperature liquid. The expansion valve also controls the flow of the refrigerant into the evaporator, depending on the cooling load.

References:

1: CDCP Preparation Guide, page 19, section 2.3.3 2: The Refrigeration Cycle5, page 1, section 1 3: Fundamentals of Cooling in Data Center6, page 1, section 1 4: The Refrigeration System, Its Four Main Components, And Their Functions7, page 1, section 1