Exin CDCP Certified Data Centre Professional (CDCP) Exam Practice Test

Measuring business value is the process of assessing the benefits and costs of IT investments and initiatives in relation to the strategic objectives and priorities of the organization. One of the factors that can be used to measure business value is scalability, which is the ability of a system or component to handle increasing workloads or demands without compromising performance, quality, or functionality. Scalability is important for business value because it enables the organization to adapt to changing market conditions, customer expectations, and growth opportunities. Scalability can also reduce operational costs, increase efficiency, and improve customer satisfaction. Therefore, scalability is one of the factors that can be used in measuring business value.

According to the Certified Data Centre Professional (CDCP®) reference materials, ICT (Information and Communication Technology) equipment such as servers, switches, and storage devices generate sensible heat. Sensible heat is the heat energy that causes a change in temperature of the air but does not contribute to humidity or moisture content. This is in contrast to latent heat, which involves a change in moisture (humidity) in the air, such as from evaporation or condensation.

ICT equipment does not introduce moisture into the environment; it only raises the temperature of the surrounding air, making it sensible heat. Proper data center cooling focuses on removing this sensible heat load to maintain optimal equipment operating conditions. Latent heat loads, such as those from people or water leaks, are typically not generated by ICT equipment and are managed differently in facility design.

Radiant heat is a minor consideration and typically refers to heat transferred by electromagnetic waves (e.g., from sunlight or hot surfaces), not the primary mode of heat transfer from ICT equipment, which is primarily through convection (airflow) and is measured as sensible heat.

A service corridor is a dedicated space within or adjacent to a data centre that allows access to the supporting facilities, such as power, cooling, fire suppression, security, and cabling systems, without interfering with the computer room operations. A service corridor helps to isolate the noise, vibration, heat, and dust generated by the supporting facilities from the sensitive equipment in the computer room. A service corridor also enhances the safety and efficiency of the maintenance and monitoring activities, as well as the flexibility and scalability of the data centre design.

According to the CDCP Preparation Guide1, risk can be defined as the product of impact and probability. Impact is the measure of the negative consequences or losses that may result from a risk event, such as downtime, data loss, or damage to the data centre. Probability is the measure of the likelihood or frequency of a risk event occurring, based on historical data, expert judgment, or statistical analysis. By multiplying impact and probability, risk can be quantified and compared, which helps in prioritizing and mitigating the risks. For example, a risk event that has a high impact but a low probability may have the same risk level as a risk event that has a low impact but a high probability.

According to the IEEE definition, reliability is the ability of a system or component to perform its required functions under stated conditions for a specified period of time. Reliability is a measure of how often a system or component fails, and how long it takes to recover from a failure. Reliability is closely related to availability, which is the degree to which a system or component is operational and accessible when required for use. Reliability and availability are both affected by factors such as design, maintenance, testing, and environmental conditions.

According to the CDCP® Preparation Guide, smoke detectors are the most common type of fire detection devices used in data centers, as they can detect a fire in its early stages and provide early warning to the occupants and authorities. Smoke detectors can be either spot-type or air-aspirating, depending on the design and goals of the data center. Spot-type detectors are inexpensive and simple, but may cause activation delay and false alarms. Air-aspirating detectors are more sensitive and reliable, but may require more maintenance and installation costs. Both types of detectors should be installed in accordance with the relevant standards and codes, such as NFPA 72 and EN 54.

A computer room air handling unit (CRAH) is a device that uses circulating chilled water to remove heat from the data center environment. A CRAH consists of a fan, a coil, and a filter. The fan draws the warm air from the data center and passes it through the coil, where the heat is transferred to the chilled water. The chilled water is supplied by a chiller or a cooling tower, and the cooled air is returned to the data center. A CRAH is different from a computer room air conditioning unit (CRAC), which uses a refrigerant instead of chilled water to cool the air.

FM200 (HFC-227) is a clean agent fire suppression system that uses a high-pressure gas to extinguish fires by reducing the oxygen concentration and absorbing the heat. FM200 is stored in cylinders at pressures of up to 42 bar (600 psi) and is released through nozzles into the protected area. Because of the high pressure, the nozzles must be mounted with two brackets to prevent them from moving or breaking during discharge. The brackets must be securely attached to the ceiling or wall and aligned with the nozzle outlet. The nozzle outlet must also be free of any obstructions that could affect the discharge pattern or distribution.

Data centre design and infrastructure standards can vary from country to country, depending on the local regulations, codes, and practices. Therefore, it is important to check the local standards before designing, building, or operating a data centre in a specific location. Compliance to only international standards may not be sufficient or adequate to meet the local requirements, which could result in legal, financial, or operational risks. For example, some countries may have stricter fire safety, environmental, or energy efficiency standards than the international ones. Some countries may also have different electrical standards, such as voltage, frequency, or plug types. By checking the local standards, you can ensure that your data centre is compliant, safe, and efficient in the local context.

As per Certified Data Centre Professional (CDCP®) reference materials, Common Mode Noise (CMN) is a type of electrical noise that appears equally on the line and neutral wires with respect to ground, and it can negatively affect sensitive ICT equipment. Excessive CMN at the rack level can lead to data errors, communication problems, equipment malfunctions, or even hardware damage.

The CDCP® training and the official exam preparation guide specify that the preferred level of Common Mode Noise at the rack should be less than 1 Volt, and under no circumstances should it exceed 3 Volts. Keeping CMN at these levels helps ensure the stable and reliable operation of critical data center infrastructure. Higher CMN levels indicate grounding or bonding issues, or possibly interference from electrical or mechanical sources, and must be addressed promptly.

Options A and B (CMN above 5 or 10 Volts) are not acceptable and would present a serious risk to ICT equipment operation and data integrity. Option D is incorrect, as CMN absolutely does affect ICT equipment.

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.

The UPS (uninterruptible power supply) is a device that provides backup power to the ICT equipment in case of a power outage or a power quality issue. The UPS should be dedicated to the ICT equipment only, and not to other loads, such as lighting, cooling, or security systems. This is because connecting fluorescent lights to the same UPS as the ICT equipment can cause several problems, such as:

•Reducing the battery runtime of the UPS, which may not be enough to support the ICT equipment until the backup generator kicks in or the utility power is restored.

•Increasing the harmonic distortion of the UPS output, which can affect the performance and reliability of the ICT equipment and the UPS itself.

•Creating electromagnetic interference (EMI) or radio frequency interference (RFI), which can disrupt the communication and data transmission of the ICT equipment.

•Triggering false alarms or tripping the circuit breakers of the UPS, which can cause downtime or data loss.

Therefore, fluorescent lights should not be connected to the same UPS that supports the ICT equipment. Instead, they should be connected to a separate power source, such as the utility power, the backup generator, or a different UPS.

Measuring “Business Values” begins first with budgeting and identifying the costs associated with the project. This includes understanding the economic impact of the project, such as the cost of labor, materials, and other resources. It is also important to evaluate the return on investment (ROI) of the project, which will help to determine its overall value. Additionally, it is important to consider the long-term impact of the project and its potential to add value to the business in the future.

According to the EPI Data Centre Professional (CDCP®) Preparation Guide, failure is defined as “the termination of the ability of a product to perform its required function” (page 9). Failure can occur due to various reasons, such as wear and tear, design flaws, human errors, environmental factors, or external events. Failure can affect the availability, reliability, and performance of a product, system, or service.

Escape route signage should be placed at every door providing a pathway to the exit or the assembly area, according to the CDCP Preparation Guide1 and the EU Safety/Health Signs Directive2. Escape route signage is used to guide the occupants of the data centre from wherever they are in the building, via a place of relative safety (the escape route), to the place of ultimate safety (the assembly area). Escape route signage should not be limited to only emergency escape doors or the main entrance of the data centre building, as these may not be accessible or visible from all locations. Escape route signage should also not include doors that do not lead to the exit or the assembly area, such as riser doors, doors of storage closets, or doors of other rooms, as these may confuse or mislead the occupants. Escape route signage should be placed at every door that provides a pathway to the exit or the assembly area, and should indicate the direction and distance of the escape route using pictograms, arrows, and words. Escape route signage should also be designed and installed in accordance with the relevant standards and codes, such as BS 5499 and ISO 7010.

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.

The current recommended temperature for ICT equipment as described in the ASHRAE TC 9.9 guideline is 18-27 C (64.4 - 80.6°F). This is the recommended range for the dry-bulb temperature at the inlet of the servers, which is the most critical parameter for ensuring the optimal performance and reliability of the ICT equipment. The recommended range is based on the thermal specifications of the majority of the ICT equipment in the market, as well as the energy efficiency and environmental considerations of the data centre cooling systems. The recommended range is suitable for Classes A1 to A4 of the ASHRAE thermal guideline classes, which cover different types and generations of ICT equipment.

According to the EPI Data Centre Training Framework, EMF is a form of electromagnetic interference (EMI) that can disrupt or damage the normal operation of electronic devices, such as servers, network cables, and IT equipment1. High levels of EMF can be generated by power equipment, cell phones, microwaves, TV and radio signals, etc., and can cause data corruption, data loss, system malfunction, and crashes23. Therefore, EMF can cause data centre failures and affect the availability, performance, and security of the data centre. To prevent or mitigate EMF, data centres should follow the best practices for data centre design, layout, cabling, grounding, shielding, and testing14.

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.

According to the Raised Floor Installation Manual, the best practice for cutting holes in the raised floor tile is to draw a cross on the tile and when making a cut-out do not touch a line and avoid the corners1. This ensures that the structural integrity and load-bearing capacity of the tile are not compromised. Cutting holes anywhere, touching the line, or cutting the corners can weaken the tile and cause it to crack or collapse1. Additionally, the manual recommends using a drill press or a reciprocating saw with a metal or bi-metal cutting blade, and deburring all sharp edges1.

Data centres are essential for supporting the IT operations and applications of various businesses across different industries. Data centre downtime can have a negative impact on the business results, such as loss of revenue, customer satisfaction, productivity, reputation, and competitive advantage. According to a web search, the average cost of data centre downtime in 2020 was $8,851 per minute, and the average duration of a data centre outage was 95 minutes1. This means that a typical data centre outage could cost a business over $840,000 in direct and indirect losses1. Therefore, data centre downtime can have a significant impact on the business results, regardless of the industry or sector.

According to the EPI Data Centre Training Framework, an isolation transformer is a device that transfers electrical power from one circuit to another without changing the voltage or frequency, but providing galvanic isolation1. Galvanic isolation means that there is no direct electrical connection between the input and output circuits, which can prevent ground loops, reduce noise, and improve safety2. An isolation transformer can also provide voltage stepdown or stepup, create a local ground-bonded neutral, reduce harmonic currents, and provide taps for abnormal mains voltage3.

The location of the isolation transformer in relation to the ICT equipment depends on the purpose and design of the transformer. In general, the isolation transformer should be as close as possible to the ICT equipment, but taking into account potential EMF4. EMF is a form of electromagnetic interference (EMI) that can affect the performance and reliability of the ICT equipment5. The closer the isolation transformer is to the ICT equipment, the shorter the cable length and the lower the voltage drop and power loss4. However, the isolation transformer should also be far enough from the ICT equipment to avoid EMF, which can be reduced by using proper shielding, grounding, and spacing5.

The isolation transformer should not be installed as far away as possible to the ICT equipment, as option B suggests, because this would increase the cable length and the voltage drop and power loss4. The isolation transformer does not have to be installed within the power entry point of the building, as option C suggests, because this is not a requirement of the electrical code or regulation, and it may not be optimal for the data centre power system. The isolation transformer should not be installed within the rack in which the ICT equipment has been installed, as option D suggests, because this would increase the heat load and the noise level in the rack, and it may not fit in the rack space.

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.

The objective of data center fire protection is to suppress or extinguish a fire before it can cause significant damage to the equipment, personnel, or business continuity. Fire suppression systems are designed to reduce the heat, oxygen, or fuel elements of the fire triangle, and to limit the spread of fire and smoke. Fire suppression systems can be classified into two types: water-based and gas-based. Water-based systems include sprinklers, mist, and water spray systems, which use water as the extinguishing agent. Gas-based systems include inert gas, halocarbon, and clean agent systems, which use gases or chemicals as the extinguishing agent. The choice of fire suppression system depends on several factors, such as the fire risk, the type of fuel, the environmental impact, the reliability, the cost, and the compatibility with the data center equipment and operations.

IP protection grades are a way of showing the effectiveness of electrical enclosures in blocking foreign bodies such as dust, moisture, liquids, and accidental contact. IP stands for Ingress Protection or International Protection, and it is defined by the international standard IEC 60529. IP ratings consist of the letters IP followed by two digits and an optional letter. The first digit indicates the level of protection the enclosure provides against access to hazardous parts and the ingress of solid foreign objects. The second digit indicates the level of protection the enclosure provides against the ingress of water or fluids. The higher the number, the better the level of protection. For example, IP65 means the enclosure is dust-tight and can withstand water jets from any direction. IP68 means the enclosure is dust-tight and can be submerged in water under specified conditions.