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New 2026 Latest Questions CDCS Dumps - Use Updated EXIN Exam
EXIN CDCS Exam Syllabus Topics:
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NEW QUESTION # 39
What is a potential disadvantage of using water mist as a fire extinguishing system?
- A. It will rapidly increase the humidity level in the data center, which can cause a potential risk for the operation of the equipment
- B. It extracts oxygen from the air creating a potential risk for humans inside the computer room
- C. It has droplets that are too small (100-120 microns) so it can only be used for small fires
- D. It only uses 10% of the water normally used in a water-based fire suppression, which might not be enough to suppress the fire
Answer: A
Explanation:
A potential disadvantage of using a water mist fire suppression system is that it can rapidly increase the humidity within the data center, which may pose risks to sensitive electronic equipment. Excessive humidity can lead to condensation, which could damage electronics and lead to short circuits or corrosion over time.
Detailed Explanation:
Water mist systems use fine droplets to suppress fires by cooling and displacing heat. However, the moisture generated may raise the humidity level to the point where it exceeds safe operational limits for IT equipment.
Therefore, while water mist systems are effective in fire suppression, they may not be ideal in environments where high humidity could damage sensitive equipment.
EPI Data Center Specialist References:
EPI guidelines advise considering the impact of humidity from fire suppression systems, particularly in environments housing electronic equipment. It's essential to weigh the benefits of fire suppression against potential risks to operational equipment when choosing suppression methods.
NEW QUESTION # 40
What is the main advantage of using an End-of-Row (EoR) design?
- A. You need a separate rack to install all your EoR switches
- B. A single Top-of-Rack (ToR) switch is more expensive than an EoR switch
- C. There will be fewer switches to manage (corrected typing: original said "more")
- D. A ToR switch has only optical interfaces
Answer: C
Explanation:
EoR centralizes access/aggregation switches at the end of each row, reducing the number of access switches compared with ToR (one per rack), which simplifies management and often lowers Ops costs.
* A, D are incorrect generalizations.
References: ANSI/TIA-942-B §8 (Telecommunications infrastructure-HDA/EoR/ToR discussion); Cisco Data Center Access Layer CVD (EoR vs ToR design considerations).
NEW QUESTION # 41
A new facility requires electrical distribution of 100A to be installed in the computer room, 1 m (3 ft) above sensitive IT equipment. What type of system minimizes EMF impact?
- A. Install three-phase power cabling based on three individual core wires
- B. Install bus bar trunking
- C. Install three-phase power cabling based on a combined cable (e.g., XLPE)
- D. Install single-phase power cabling
Answer: C
Explanation:
Electromagnetic fields are generated by current-carrying conductors. To minimize stray EMF, phase conductors should be physically close and balanced. A three-phase combined cable (all phase conductors and neutral in one sheath) ensures magnetic fields cancel each other due to phase opposition.
If phases are run separately (answer B), the separation increases loop area and magnetic field leakage. Single- phase cabling (A) is even worse because current does not balance across three phases. Bus bar trunking (C) provides physical support but often separates conductors, which may worsen EMF if not specifically shielded.
Therefore, the correct solution is three-phase combined cable (often XLPE-insulated). This design reduces EMF impact to within ANSI/TIA-942 and IEEE recommendations.
References: IEEE Std 141 (Red Book - Power Distribution), ANSI/TIA-942-B §6.6.4, IEC 60364 (Wiring Systems and EMF).
NEW QUESTION # 42
When installing a raised floor, can we use a spirit level bar to level the floor?
- A. Yes, using a spirit level bar for raised floors higher than 40 cm is preferred.
- B. Yes, but spirit level bars can only be used in the vertical plane.
- C. Yes, spirit level bars can be used as long as their length is longer than 60 cm/2 ft (the size of a typical raised floor tile).
- D. No, because using a spirit level bar, a measurement error will be transferred from pedestal to pedestal.
Answer: D
Explanation:
A spirit level bar should not be used for leveling a raised floor, as measurement errors are likely to propagate from one pedestal to the next. Spirit levels can introduce cumulative errors, leading to uneven floors, particularly in large installations where precise leveling is critical.
Detailed Explanation:
Using a laser level or a precision leveling device is recommended to ensure accuracy across all floor tiles. Spirit levels, while adequate for short spans, can transfer small inaccuracies from one pedestal to another, which can cause alignment issues and floor instability over time.
EPI Data Center Specialist References:
EPI data center guidelines discourage the use of spirit levels for raised floors. Instead, they advocate for precision tools like laser levels that ensure consistency and accuracy in large-scale installations, aligning with best practices for raised floor construction.
NEW QUESTION # 43
What is the floor loading requirement for a Rated-3 data center according to ANSI/TIA-942?
- A. 12 kPa
- B. 7.2 kPa
- C. 8.4 kPa
- D. 15 kPa
Answer: A
Explanation:
ANSI/TIA-942 specifies minimum floor live load capacities based on Rated levels:
* Rated-1/2: ~7.2-8.4 kPa
* Rated-3: 12 kPa
* Rated-4: 15 kPa
These values ensure raised floors can support racks, cabling trays, cooling units, and maintenance loads without structural compromise. For Rated-3, concurrent maintainability requires higher floor robustness to handle additional infrastructure.
Therefore, the correct requirement is 12 kPa.
References: ANSI/TIA-942-B §6.3.5 (Floor Loading), CISCA Raised Floor Design Guide.
NEW QUESTION # 44
A data center has its own power supply from the public utility and receives chilled water supply from the building owner.
What needs to be taken into consideration when calculating the PUE?
- A. Nothing, as the chiller plant in the building also uses electrical power
- B. You will need to take the value for COP of the chiller plant into consideration
- C. PUE calculations are not possible in shared buildings
- D. You will need to take a weight factor of 0.4 for district chilled water into consideration
Answer: D
Explanation:
When calculating Power Usage Effectiveness (PUE) in a data center that uses chilled water from an external source, like from a building owner, a weight factor for district chilled water must be applied. This is because PUE calculations aim to measure the energy efficiency of the data center's own operations, and external utilities like district chilled water aren't directly powered by the data center. A weight factor of 0.4 is typically used to account for the energy consumed to produce and deliver the chilled water, reflecting the indirect impact on the data center's total energy consumption.
Detailed Explanation:
PUE is calculated as the ratio of the total facility energy to the IT equipment energy. If the cooling is provided by an external chilled water source, it's necessary to adjust the calculations to accurately reflect the energy impact. By incorporating the 0.4 weight factor, data centers can calculate a more accurate PUE, aligning with standard methods and industry best practices.
EPI Data Center Specialist References:
EPI training on PUE highlights the importance of adjusting for external energy sources, such as district cooling, in the calculations. This ensures that PUE values remain accurate and comparable across different data centers, even when external utilities are used.
NEW QUESTION # 45
In order to save energy, you are going to install an automated system to switch off lights. What should be taken into consideration when installing such a system?
- A. Security guards should perform regular inspections verifying the system works.
- B. At all times, the levels should allow for security cameras to function properly.
- C. The system should not be based on motion detection as the lights might suddenly switch off while staff is still at work.
- D. It is not advisable to use such a system since it will reduce the lifetime of LED lighting.
Answer: B
Explanation:
When installing an automated lighting system, especially in a security-sensitive area like a data center, it's essential to ensure that lighting levels support security camera functionality at all times. Sufficient lighting is necessary for cameras to capture clear footage, ensuring continuous monitoring and security regardless of occupancy.
Detailed Explanation:
Automated lighting based on occupancy or time settings can reduce energy costs, but it must be configured to maintain adequate illumination for surveillance. Security cameras require minimum lighting levels to operate effectively, so lighting should be configured to avoid compromising security.
EPI Data Center Specialist References:
EPI emphasizes security and safety in data centers, advising that lighting systems should maintain levels conducive to effective surveillance, ensuring operational security even when lights are automatically controlled.
NEW QUESTION # 46
Which formula is correct?
- A. Phase-to-Neutral Voltage = Phase-to-Phase voltage /1.732
- B. Phase-to-Neutral Voltage = Phase-to-Neutral voltage * 1.732
- C. Phase-to-Neutral Voltage = Phase-to-Phase voltage * 1.732
- D. Phase-to-Neutral Voltage = (Phase-to-Phase voltage * 1.732) / Phase-to-Neutral Voltage
Answer: A
Explanation:
The correct formula for calculating Phase-to-Neutral Voltage in a three-phase power system is Phase-to- Neutral Voltage = Phase-to-Phase Voltage / 1.732. This formula applies to balanced three-phase systems, where 1.732 (or #3) represents the relationship between line-to-line and line-to-neutral voltages.
Detailed Explanation:
In three-phase systems, Phase-to-Phase Voltage is higher than Phase-to-Neutral Voltage by a factor of #3.
Dividing the phase-to-phase voltage by 1.732 gives the phase-to-neutral voltage, which is critical for understanding power distribution in three-phase electrical systems commonly found in data centers.
EPI Data Center Specialist References:
EPI electrical training highlights the importance of knowing these calculations for designing and maintaining balanced power systems, which are essential for stable and efficient data center operations.
NEW QUESTION # 47
What indicates the breaking capacity of a fuse or breaker?
- A. Mechanical strength of the casing of a fuse or breaker.
- B. The current that a fuse or breaker is able to interrupt without being destroyed or causing an electric damaging arc.
- C. The maximum voltage, in case of an electrical surge, that the fuse or breaker can handle without being destroyed or causing an electric damaging arc.
- D. The current at which the device will trip.
Answer: B
Explanation:
The breaking capacity of a fuse or breaker indicates the maximum current it can safely interrupt without being damaged or creating a dangerous arc. This value is crucial for ensuring that the device can handle fault conditions and prevent equipment damage or fire risks due to excessive current flow.
Detailed Explanation:
The breaking capacity, also known as the interrupting rating, ensures that the fuse or breaker can safely handle fault currents up to a specified limit. Exceeding this capacity could result in the device failing to interrupt the current, potentially causing hazardous conditions like electrical arcs.
EPI Data Center Specialist References:
EPI training underscores the importance of matching fuses and breakers with appropriate breaking capacities for the anticipated fault levels in data centers to ensure reliable and safe operation.
NEW QUESTION # 48
You are changing the design of the fire suppression system for your computer room from a halocarbon fire suppression system into an inert-based fire suppression system. Could you use the same formula to calculate the gas content for the gas?
- A. Yes, as long as you use the same units of measure, i.e., kg/m³ or lbs/ft³.
- B. Yes, as long as you take the difference between the net and gross volume into account.
- C. Yes, as long as you change the 'S' factor of the formula to reflect the gas type used.
- D. No, there is a significant difference in the formula for the different types of fire suppression gases.
Answer: D
Explanation:
The formula used to calculate the gas content differs significantly between halocarbon and inert-based fire suppression systems. Halocarbon systems function by absorbing heat, while inert systems work by reducing oxygen levels. Due to these differences in fire suppression mechanisms, distinct formulas are applied, factoring in the specific properties of each gas type and the required concentration levels.
Detailed Explanation:
Halocarbon systems like FM200 require a formula that accounts for the concentration needed for cooling, while inert gases like nitrogen or argon need a formula that calculates the volume based on oxygen displacement. As the design concentration and characteristics of these gases differ, it's essential to use the correct formula specific to the gas type.
EPI Data Center Specialist References:
EPI recommends consulting the specific design requirements and formulas provided by each gas manufacturer when switching fire suppression systems to ensure the correct amount of gas is deployed for effective fire suppression.
NEW QUESTION # 49
The computer room has high levels of H2S gas contamination. What is the best option to resolve this issue?
- A. Install air-scrubbers.
- B. Vacuum the whole room using a HEPA/S-Class-based filter.
- C. Provide more air changes per hour by adding more fresh air to the computer room.
- D. Clean the room and racks with a damp/wet cloth.
Answer: A
Explanation:
High levels of H2S (hydrogen sulfide) gas contamination in a computer room are best addressed by installing air-scrubbers. Air-scrubbers can effectively filter out contaminants, including corrosive gases like H2S, ensuring clean air circulation and protecting sensitive IT equipment from potential corrosion and damage.
Detailed Explanation:
Air-scrubbers are designed to remove various airborne contaminants and are particularly useful in environments where corrosive gases are present. These systems use filters or chemical reactions to neutralize harmful substances, making them ideal for data centers that need to maintain high air quality for equipment reliability.
EPI Data Center Specialist References:
EPI guidelines suggest air-scrubbing technologies to remove contaminants that pose risks to electronic equipment, maintaining air quality and reducing corrosion risk.
NEW QUESTION # 50
When designing a data center network, your company wants to minimize the number of network switches to manage.
What type of physical cabling layout would be the best choice?
- A. It does not matter as the number of switches is not influenced by the physical cabling layout
- B. EoR (End of Row) design
- C. Star network design using coaxial cables
- D. ToR (Top of Rack) design
Answer: B
Explanation:
An End of Row (EoR) design minimizes the number of network switches, as multiple racks can share a single switch at the end of a row, reducing switch counts and simplifying management. This design centralizes network switching to fewer points, which reduces the complexity and number of switches required compared to a Top of Rack (ToR) design, where each rack typically has its own switch.
Detailed Explanation:
In EoR designs, each row has a single network switch that handles the connections for all racks within that row. This reduces the number of individual switches needed and centralizes network management, which is ideal for minimizing equipment and simplifying infrastructure in the data center.
EPI Data Center Specialist References:
EPI promotes the EoR design as a way to reduce switch counts and streamline management in data centers. This configuration allows for easier scaling and maintenance while maintaining efficient network connectivity.
NEW QUESTION # 51
The pipes of a VESDA smoke detection system are installed at the air intake of the air conditioner inside the computer room.
Is this a good practice from an early smoke detection point of view?
- A. Yes, as this reduces the amount of piping to be installed in the data center, as all air will go through the air conditioner.
- B. No, the piping should be installed at the air exhaust of the air conditioner, as there can also be a fire inside the air conditioner itself.
- C. No, it will give a longer reaction time for the smoke detection system and there might also be bypass airflow.
- D. It depends on the type of gas-based fire suppression which will be installed.
Answer: C
Explanation:
For optimal early smoke detection in a data center, it is crucial that the Very Early Smoke Detection Apparatus (VESDA) system be installed at locations where smoke will be detected as soon as it appears. Positioning the VESDA pipes at the air intake of the air conditioner inside the computer room is not ideal. This placement could result in a delayed detection response and the potential for bypass airflow to occur, which would impede the system's ability to detect smoke effectively.
Detailed Explanation:
When VESDA pipes are installed at the air intake, the detection system relies on the smoke to be drawn into the air conditioning unit before detection can occur. This setup increases the reaction time as the smoke has to travel through the intake and get processed by the air conditioner. Furthermore, bypass airflow-a phenomenon where not all the air containing smoke particles passes through the VESDA pipes-could also delay or even prevent the system from detecting smoke early.
Ideally, VESDA pipes should be positioned where smoke is likely to accumulate first, such as near the ceiling or in the return airflow path to detect smoke at the earliest possible stage. This ensures that the detection system can quickly trigger alarms, providing more time to address potential fire hazards.
EPI Data Center Specialist References:
EPI Data Center Specialist training highlights that smoke detection should prioritize early response capabilities to maximize safety. The preferred installation for VESDA pipes is generally at points where smoke would naturally accumulate, rather than relying on air conditioning intakes where airflow can vary and delay detection. In their course materials, EPI emphasizes minimizing reaction time and reducing the impact of airflow dynamics on smoke detection efficiency.
NEW QUESTION # 52
Three data centers are benchmarked on facilities energy efficiency.
Data center A has achieved a PUE of 2.45.
Data center B has achieved a PUE of 1.20.
Data center C has achieved a PUE of 1.90.
Which of the data centers is operating at the highest facility efficiency?
- A. PUE does not indicate efficiency
- B. Data center C
- C. Data center B
- D. Data center A
Answer: D
Explanation:
A Power Usage Effectiveness (PUE) of 1.20 (achieved by Data Center B) indicates the highest facility efficiency among the three data centers. A lower PUE value signifies better energy efficiency, as it means that a greater proportion of the total energy consumed is used directly for IT equipment rather than for cooling, lighting, or other facility needs.
Detailed Explanation:
PUE is calculated as the ratio of total facility energy to IT equipment energy. A PUE close to 1.0 suggests that almost all the energy is dedicated to computing processes, with minimal overhead. With PUE values of 2.45, 1.20, and 1.90, Data Center B (1.20) operates most efficiently by devoting a higher percentage of its total energy to IT equipment.
EPI Data Center Specialist References:
The EPI curriculum emphasizes PUE as a key metric for data center efficiency, with lower values representing better performance. Achieving a PUE near 1.0 aligns with industry best practices for energy-efficient data center design and operation.
NEW QUESTION # 53
What is the advantage or disadvantage of using MPO (Multi-fiber Push On)/pre-terminated fiber?
- A. It is a very flexible system as it can be used for both copper cables and optical fiber cables.
- B. It speeds up installation and provides an easy upgrade to transmission speeds up to 40 Gbit/s -100 Gbit/s.
- C. There is no advantage, as it creates additional heat load in the data center.
- D. There is no advantage, as it cannot be used with OM4 optical fiber cables.
Answer: B
Explanation:
MPO (Multi-fiber Push On) pre-terminated fiber offers the advantage of quick installation and supports high-speed upgrades up to 40 Gbit/s and 100 Gbit/s. This technology simplifies connections by allowing multiple fibers to be connected in a single plug-and-play module, reducing installation time and making future expansions or upgrades to higher speeds easier.
Detailed Explanation:
MPO connectors consolidate multiple fiber connections into a single interface, which simplifies cable management and reduces installation complexity. This setup is particularly beneficial in data centers where high-speed networks are essential, and where rapid deployment is necessary. MPO pre-terminated fiber also supports the use of OM4 fiber, making it compatible with existing high-performance cabling infrastructure.
EPI Data Center Specialist References:
EPI training highlights that pre-terminated fiber solutions, like MPO, can greatly enhance efficiency in data centers. By reducing installation time and providing scalability for higher transmission speeds, they align with best practices for maintaining flexible and future-ready network infrastructure.
NEW QUESTION # 54
A computer room is fitted with a hypoxic-based fire suppression system. On what principle does it work?
- A. It removes the fuel from the fire
- B. It lowers the oxygen levels in the room
- C. It uses water as an extinguisher
- D. It removes the heat from the fire
Answer: B
Explanation:
Hypoxic air systems continuously reduce the oxygen concentration in the protected area to below the level required for combustion (typically 15-16%), while still remaining safe for human occupancy (>14%). By lowering oxygen concentration, ignition and flame propagation are prevented.
This is different from halocarbon or inert-gas clean agents, which flood the room only upon detection of fire.
Hypoxic systems are preventive, creating a permanent fire-retardant environment.
They do not remove heat (A), fuel (C), or use water (D). Their key mechanism is oxygen displacement.
References: ISO 20338 (Oxygen Reduction Systems), NFPA 770 (Standard on Hybrid Fire Extinguishing Systems).
NEW QUESTION # 55
You are allowed to use a calculator for this question. A battery bank is rated at a total capacity of 600 Ah.
Calculate how much charging current the rectifier should be able to supply as charging current.
- A. 60 Amperes
- B. 12 Amperes
- C. 80 Amperes
- D. 30 Amperes
Answer: D
Explanation:
To determine the charging current for a battery bank, a general rule of thumb is that the charging current should be 5% of the total battery capacity. For a battery rated at 600 Ah, this calculation would be:
600 Ah×0.05=30 Amperes600 \, \text{Ah} \times 0.05 = 30 \, \text{Amperes}600Ah×0.05=30Amperes This ensures the battery is charged efficiently without overloading the rectifier or risking battery damage.
Detailed Explanation:
Battery charging current is typically set as a percentage of the battery's capacity to balance effective charging with longevity and safety. A 5% charging rate is standard for lead-acid batteries, which would be 30 Amperes for a 600 Ah battery bank.
EPI Data Center Specialist References:
EPI standards recommend calculating charging currents based on a percentage of the battery capacity to ensure safety and efficiency, aligning with best practices for battery management in data centers.
NEW QUESTION # 56
You have three UPS systems connected in parallel. The UPS systems have an imbalance in the load sharing of approximately 20%.
What should you recommend?
- A. Review the cable lengths of each UPS to the common busbar
- B. Nothing, there is no reason for any concern
- C. Review the common mode noise levels within the computer room
- D. Review the harmonics levels within the computer room
Answer: A
Explanation:
An imbalance in load sharing between UPS systems connected in parallel can often result from unequal cable lengths to the common busbar. If the cabling from each UPS to the busbar varies significantly in length, it can lead to differences in impedance, resulting in uneven load distribution. Ensuring that cable lengths are consistent helps to balance the load sharing across the UPS systems.
Detailed Explanation:
Parallel UPS systems rely on uniform impedance to share loads evenly. Differences in cable lengths cause variations in resistance, leading to one or more UPS units carrying a disproportionate share of the load. Standardizing cable lengths ensures equal impedance, which promotes balanced load sharing and prevents one UPS from being overburdened, thus maintaining overall system reliability.
EPI Data Center Specialist References:
EPI guidelines recommend checking cable lengths when load imbalances occur in parallel UPS configurations. Ensuring equal lengths is a common method to resolve impedance issues that affect load distribution, which is critical for the stable operation of redundant power systems.
NEW QUESTION # 57
The logical overview of the data center looks as pictured. To what TIA-942 Rating is this design made based on electrical only?
- A. Rating - 4
- B. Rating - 1
- C. Rating - 2
- D. Rating - 3
Answer: A
Explanation:
The electrical design shown in the diagrams represents a TIA-942 Rating-4 configuration. This design includes full redundancy and fault tolerance, as demonstrated by the dual power distribution paths from the utility supply to the critical loads. Each power distribution path is equipped with its own UPS, ensuring that the ICT equipment and mechanical equipment have uninterrupted power in case of any single point of failure.
Detailed Explanation:
A Rating-4 data center requires two independent power paths that are fully redundant and capable of supporting the load independently. In the diagrams:
* There are dual feeds from the utility supply, each going through separate transfer switches and power distribution paths.
* Both paths have backup sources (+1) and serve critical components through separate UPS systems, providing a completely redundant setup.
* The design also includes redundant paths to the mechanical equipment and ICT equipment, which further indicates the fault-tolerant characteristics of a Rating-4 infrastructure.
This setup allows for concurrent maintainability and ensures that no single failure in power distribution or UPS can impact the data center's operation, which is characteristic of the highest Tier/Rated-4 classification.
EPI Data Center Specialist References:
EPI guidelines confirm that TIA-942 Rating-4 requires full redundancy and fault tolerance for electrical infrastructure, ensuring continuous operation even during maintenance or failure events. This design meets all those requirements, thus aligning with Rating-4 standards.
NEW QUESTION # 58
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