EXIN EXIN Certifications CDCP Questions & Answers

• Question 31:

  is the arithmetic mean of time between the failing and the subsequent running of the system in a particular time period.

  A. MTBF

  B. MCBF

  C. MLBF

  D. MTTR

  Correct Answer: A

  MTBF stands for Mean Time Between Failures, and it is the arithmetic mean of time between the failing and the subsequent running of the system in a particular time period. MTBF is a measure of reliability that indicates how often a system or component fails during its operation. MTBF can be calculated by dividing the total operating time by the number of failures over a given period. For example, if a system operates for 1000 hours and experiences 5 failures, the MTBF is 1000/5 = 200 hours.

• Question 32:

  Does shielded twisted pair network cabling provide protection against EMF from power cables?

  A. Yes, but only if the power cable is placed in a tre-foil cable arrangement.

  B. Yes, as the shielding for twisted pair network cabling is specifically design for low frequency EMF protection.

  C. No, the shielding is designed for alien cross-talk between network cables, it provides no or little protection against low frequency EMF.

  D. No, the shielding for twisted pair network cabling is for physical protection against vandalism and accidental cutting of the cable.

  Correct Answer: C

  Shielded twisted pair cables (STP) are Ethernet cables that feature additional protection against electromagnetic interference from external sources, such as radio waves, microwaves, or other network cables. This is achieved by wrapping each pair of wires with a conductive shield, usually made of foil or braided wire, and then enclosing the entire cable with another shield layer. However, this shielding is not effective against low frequency electromagnetic fields (EMF) from power cables, which can induce currents and voltages in the network cables and cause signal distortion or data loss. Low frequency EMF can only be reduced by increasing the distance between the power and network cables, or by using a tre-foil cable arrangement, which is a special configuration of three power cables twisted together to cancel out the magnetic fields they generate.

• Question 33:

  What is the primary reason to install a monitoring system in the data centre?

  A. To notice abnormalities early so that actions can be taken to avoid disasters

  B. To create a proper asset database

  C. To implement automated change management

  D. To be able to collect data for capacity planning

  Correct Answer: A

  The primary reason to install a monitoring system in the data centre is to notice abnormalities early so that actions can be taken to avoid disasters, according to the CDCP Preparation Guide1 and various web sources234. A monitoring system is a system that collects and analyzes data about the power, cooling, environmental, and security conditions in the data centre, and alerts the operators or managers about any issues or threats that may affect the performance, availability, or reliability of the data centre. A monitoring system can help to prevent or minimize the impact of disasters, such as power outages, fire, water damage, overheating, equipment failure, or cyberattacks, by providing timely and accurate information that enables fast and corrective action. A monitoring system can also help to improve the energy efficiency, capacity planning, and asset management of the data centre, by providing useful insights and trends that support informed decision making.

• Question 34:

  What should be considered when using a direct air handler for a data centre?

  A. Cost of operation as power consumption on these units tend to be higher compared to traditional air conditioning technology.

  B. Temperature, humidity and contamination of the outdoor environment.

  C. Space available inside the computer rooms as the air handler space requirement for the inside the Computer room is quite large.

  D. The availability of three-phase power due to the high power requirements of these air handler units.

  Correct Answer: B

  Direct air handlers are a type of cooling system that use outdoor air to cool the data centre. They draw in fresh air from outside, filter it, and supply it to the data centre at the desired temperature and humidity level. Direct air handlers can reduce the energy consumption and operating costs of data centres by eliminating the need for mechanical cooling or refrigeration. However, they also have some challenges and limitations that need to be considered. One of the main factors to consider when using direct air handlers for data centres is the temperature, humidity and contamination of the outdoor environment. Depending on the location and climate of the data centre, the outdoor air may not always be suitable for cooling the data centre. For example, if the outdoor air is too hot, too humid, or too polluted, it may not provide enough cooling capacity, or it may damage the IT equipment or cause corrosion. Therefore, direct air handlers need to have sensors and controls to monitor the outdoor air quality and adjust the airflow accordingly. They may also need to have backup cooling systems or supplementary cooling devices, such as evaporative coolers or heat exchangers, to cope with extreme weather conditions or peak loads.

• Question 35:

  The expected time to Recover/Repair from a system from a failure is defined as.

  A. MTBF

  B. MCBF

  C. MLBF

  D. MTTR

  Correct Answer: D

  The expected time to recover or repair from a system from a failure is defined as MTTR (mean time to recovery or mean time to repair). MTTR is the average time it takes to restore a system or product to its normal operation after a failure. MTTR includes the time spent on detecting, diagnosing, and fixing the problem. MTTR is an important metric for measuring the reliability and availability of a system or product, as well as the efficiency and effectiveness of the incident management process. A lower MTTR indicates a faster and more reliable recovery or repair process.

• Question 36:

  Which one of the following represents the three elements (oxygen, heat and fuel) to interact in order for the fire to exist?

  A. The Fire Hexagon

  B. The Fire Class

  C. The Fire Triangle

  D. The Fire Technology

  Correct Answer: C

  The fire triangle is a simple model that illustrates the three elements a fire needs to ignite: heat, fuel, and an oxidizing agent (usually oxygen). A fire naturally occurs when the elementsare present and combined in the right mixture. A fire can be prevented or extinguished by removing any one of the elements in the fire triangle.

  References: EPI Data Centre Professional (CDCP? Preparation Guide, page 9; Fire triangle - Wikipedia; The Fire Triangle Explained - Fire Action

• Question 37:

  What should be a consideration when having casters (rollers/wheels) or feet under the rack?

  A. The casters and feet should be larger to avoid a too heavy point load on the floor tile.

  B. Skirts at the bottom of the rack to avoid air flow between the hot and cold aisles.

  C. Casters and feet should be of a soft material, for example rubber, to avoid damage to the raised floor tile.

  D. Casters and feet should not be locked to ensure the racks are still able to be moved to another position.

  Correct Answer: A

  The casters and feet under the rack are used to support the weight of the rack and its equipment, and to allow the rack to be moved if needed. However, the casters and feet should also be designed to avoid putting too much pressure on the floor tile, especially if the data centre uses a raised floor system. A too heavy point load on the floor tile can cause the tile to crack, deform, or collapse, which can damage the rack, the equipment, and the underlying infrastructure. To prevent this, the casters and feet should be larger, so that they can distribute the weight over a larger area and reduce the point load. The casters and feet should also be compatible with the floor type and the load rating of the floor tile.

• Question 38:

  What is the main advantage of busbar trunking compared to stand electrical cabling?

  A. Busbar trunking is less expensive.

  B. Busbar trunking has a fixed power rating.

  C. Busbar trunking allows for flexibility.

  D. Busbar trunking can be located both overhead and under the raised floor.

  Correct Answer: C

  Busbar trunking systems are a method of power distribution using rigid copper or aluminium conductors to distribute the power around a building. Busbar trunking systems have many advantages over cables, such as lower space requirements, higher short-circuit strength, lower fire load, and easier installation. One of the main advantages of busbar trunking is that it allows for flexibility in terms of power transmission and distribution. Busbar trunking systems can be easily relocated, modified, or expanded to accommodate changes in the building layout or load demand. Busbar trunking systems can also be fitted with various components, such as tap-off units, elbows, tees, and end feed units, to provide power to different locations and consumers. Busbar trunking systems can also be installed both overhead and under the raised floor, depending on the design and preference of the building.

• Question 39:

  An optical fiber cable comes with the specifications 50/125 um.

  What do the numbers represent?

  A. The first number represents the distance for a 10 Gb/s connection; the second number represents the

  B. distance for a 1 Gb/s connection.

  C. The first number represents the diameter of the core; the second number represents the diameter of the cladding in microns.

  D. The first number represents the diameter of the core; the second number represents the actual diameter cable including the buffer and jacket.

  E. The first number represents the required distance to single-phase power cabling; the second number represents the required distance to three-phase cabling.

  Correct Answer: B

  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 (m), which are one millionth of a meter. For example, a 50/125 m cable has a core diameter of 50 m and a cladding diameter of 125 m. The coating diameter is usually 250 m, but it is not part of the specifications.

• Question 40:

  How many monitoring points should be used in Temperature Measurement?

  A. 1

  B. 2

  C. 3

  D. 4

  Correct Answer: C

  According to the EPI Data Centre Professional (CDCP? Reference Materials, the recommended number of monitoring points for temperature measurement in a data centre is 3 per rack: one at the top, one at the middle, and one at the bottom. This is to ensure that the temperature distribution within the rack is uniform and within the acceptable range for the equipment. The temperature sensors should be placed at the front of the rack, where the air enters the equipment, and not at the back, where the hot air exits.