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New 2026 Latest Questions CDCS Dumps - Use Updated EXIN Exam
NEW QUESTION # 43
You are working with a customer who requires a guarantee that THDi levels coming from the UPS should not exceed more than 3% THDi. Furthermore, he wants to run a power-efficient data center. The UPS has a 6- Pulse SCR/Thyristor based rectifier. The current load on the UPS is approximately 80%. The customer indicates they are not expecting any changes on the ICT infrastructure for the next 3 years.
What should you recommend?
- A. Install an isolation transformer rated at K13 or K20
- B. Nothing, the UPS will be able to take care of the right levels of THDi
- C. Install a passive harmonic filter on the UPS
- D. Install an active harmonic filter on the UPS
Answer: D
Explanation:
Given the customer's requirement to limit Total Harmonic Distortion (THDi) to below 3% and the presence of a 6-pulse SCR/Thyristor-based rectifier, an active harmonic filter is the best solution. A 6-pulse rectifier typically generates higher harmonic distortion, often exceeding 3%, especially under substantial loads like
80%. An active harmonic filter dynamically monitors and compensates for harmonic distortion, effectively reducing THDi and supporting a more power-efficient operation, aligning with the customer's energy efficiency goals.
Detailed Explanation:
Passive harmonic filters can reduce harmonics but are less effective at maintaining low THDi levels under varying loads. Active filters offer real-time correction and can achieve lower THDi levels than passive filters, especially in systems with fluctuating loads or where strict harmonic limits are required. Installing an active harmonic filter will ensure compliance with the specified THDi limits and optimize power quality.
EPI Data Center Specialist References:
EPI guidance on power quality management recommends active harmonic filters for environments where strict THDi levels are necessary. Active filters offer better control over harmonic levels, supporting both compliance and operational efficiency.
NEW QUESTION # 44
FM-200 is phasing out as a halocarbon gas and management has decided to replace this with the more environmentally friendly Novec-1230 gas. Should you use exactly the same formula and parameters to calculate the gas content for the Novec-1230 gas?
- A. Yes, as long as the temperature in the computer room has not changed
- B. Yes, if you take the difference between the net and gross volume into account
- C. Yes, as long as you use the same units of measure (kg/m³ or lbs/ft³)
- D. Yes, if you change the S-factor of the formula to reflect the gas type used
Answer: D
Explanation:
Halocarbon agents such as FM-200 (HFC-227ea) and Novec-1230 (FK-5-1-12) are both defined under NFPA
2001 and ISO 14520 as clean agents, but their required design concentrations and physical properties differ.
When calculating agent quantity, the minimum extinguishing concentration (MEC) and safety factor (S) must be taken into account. The S-factor is specific to each agent and reflects differences in molecular weight, density, and flame suppression chemistry.
For Novec-1230, the required design concentration is generally lower than for FM-200 (around 4.5-6% vs. 7-
9%), but the calculation formula is the same except for substituting the correct S-factor. Therefore, you cannot reuse the exact formula parameters from FM-200; you must change the S-factor and apply Novec-1230's physical constants.
This ensures compliance with NFPA 2001 Annex C, which provides correction formulas for room volume, temperature, and specific agent type. Using the wrong S-factor could result in underfilling or overfilling, compromising fire safety or increasing cost unnecessarily.
References: NFPA 2001 §5.4 (Agent Quantity), ISO 14520-5 (FK-5-1-12 properties), EXIN DCS Study Guide: Fire Suppression.
NEW QUESTION # 45
The building in which the computer room is housed is required to have a sprinkler system. The building is therefore equipped with a wet pipe system.
What action, if any, should you recommend for the computer room?
- A. Maintain the current wet pipe system.
- B. Replace the wet pipe system with a dry pipe system.
- C. Replace the wet pipe system with a pre-action system.
- D. Replace the wet pipe system with a deluge system.
Answer: C
Explanation:
In computer rooms, replacing a wet pipe system with a pre-action system is advisable. Pre-action systems provide additional protection by requiring two triggers (e.g., heat and smoke) before water is released, minimizing the risk of accidental discharge and water damage, which is crucial for safeguarding sensitive IT equipment.
Detailed Explanation:
Wet pipe systems contain water in the pipes at all times, which poses a higher risk of accidental discharge.
Pre-action systems, however, only fill the pipes with water upon detection of a fire, reducing the risk of water- related damage due to leaks or malfunctions. This approach is considered best practice for environments housing sensitive electronic equipment.
EPI Data Center Specialist References:
EPI advises using pre-action fire suppression in data centers to reduce risks associated with accidental water release, providing a safer and more controlled fire response that better protects critical infrastructure.
NEW QUESTION # 46
What is the preferred way to measure dust levels in the computer room?
- A. By opening up equipment for inspection
- B. With test coupons
- C. With an air particle hand-held analyzer
- D. By taking dust samples under the raised floor
Answer: B
Explanation:
ASHRAE TC 9.9 recommends using dust deposition coupons (also called reactivity coupons) to measure particulate contamination over time. These are small, standardized metallic plates exposed to the air that collect dust and contaminants. After a set period, they are analyzed for chemical corrosion rates and particulate buildup.
* Option A (handheld analyzers) gives spot counts of airborne particles but does not capture long-term corrosive deposition risk.
* Option C only samples underfloor plenum dust, not actual IT environment contamination.
* Option D (opening equipment) is invasive and risks voiding warranties.
Coupons provide standardized, passive, and reliable monitoring of contamination over months, making them the preferred method.
References: ASHRAE TC 9.9 "Particulate and Gaseous Contamination Guidelines," IEC 60721-3-3.
NEW QUESTION # 47
Which class of UPS is ideal for data centers?
- A. VFI (Voltage and Frequency Independent)
- B. VFD (Voltage and Frequency Dependent)
- C. First class
- D. VI (Voltage Independent)
Answer: A
Explanation:
IEC 62040 defines UPS topologies:
* VFD: Line-interactive; dependent on mains.
* VI: Stabilizes voltage but not frequency.
* VFI: Double-conversion online; fully isolates output from mains fluctuations.
Data centers require continuous, clean, and stable power. VFI is the only topology that protects against both voltage and frequency disturbances, meeting ANSI/TIA-942 Rated-3/4 requirements.
Thus, VFI is the ideal UPS class.
References: IEC 62040-3, ANSI/TIA-942-B §6.2.
NEW QUESTION # 48
What is the calculation for the desired attenuation factor for shielding material?
- A. A = M / R
Where - B. A is Attenuation
M is the maximum acceptable value
R is the real value measured - C. A = 20 log (R / M)
Where
A is Attenuation
R is the real value measured
M is the maximum acceptable value - D. A = 20 log (M / R)
Where
A is Attenuation
M is the maximum acceptable value
R is the real value measured - E. You do not have to calculate the attenuation factor for shielding material as it always has the same attenuation
Answer: B
Explanation:
The attenuation factor for shielding material is typically calculated using the formula A = 20 log (R / M). This equation provides the attenuation in decibels (dB), where R represents the measured electromagnetic field strength, and M is the maximum acceptable level. The logarithmic scale helps quantify how much the shielding reduces EMF levels relative to the maximum allowable value.
Detailed Explanation:
This formula calculates attenuation by comparing the measured value with the acceptable threshold, with the result expressed in decibels. A higher attenuation indicates more effective shielding material, essential for environments requiring robust EMF management.
EPI Data Center Specialist References:
EPI standards include the use of logarithmic formulas to evaluate attenuation levels, ensuring that shielding materials provide adequate reduction in EMF to protect sensitive equipment within data centers.
NEW QUESTION # 49
What is needed to determine the Relative Humidity (RH)?
- A. Dry bulb temperature, airflow, and conversion table
- B. Cold surface with dew collection counter
- C. Wet bulb temperature, local atmospheric pressure, and calculator
- D. Dry bulb temperature, wet bulb temperature, and psychrometric chart
Answer: D
Explanation:
Relative Humidity (RH) is defined as the ratio of the actual water vapor content in the air to the maximum possible water vapor content at a given temperature. To calculate RH:
* Dry bulb temperature (DBT): the ambient air temperature.
* Wet bulb temperature (WBT): the temperature measured by a thermometer covered with a wet wick, influenced by evaporative cooling.
Using DBT and WBT, the humidity ratio and dew point can be determined with a psychrometric chart or Mollier diagram. From there, RH is calculated as:
A black text on a white background AI-generated content may be incorrect.
Options A and B are incomplete, while option C is an experimental method, not standard practice. The recognized method is option D.
References: ASHRAE Fundamentals Handbook - Psychrometrics, ISO 7726 (Measurement of Physical Quantities in Thermal Environments).
NEW QUESTION # 50
Do you need to consider blast protection when designing a data center?
- A. Yes, blast protection is a requirement of ANSI/TIA-942.
- B. No, there is no reason for implementing blast protection as nobody can predict the impact of a bomb explosion.
- C. Yes, if the data center is a potential target or the building is located within the vicinity of (close by) a potential target.
- D. No, blast protection is not a requirement of ANSI/TIA-942.
Answer: C
Explanation:
Blast protection should be considered if the data center or its location is a potential target or is near high-risk areas. Blast protection measures can protect both personnel and infrastructure from potential explosion impacts, which could be essential in areas with heightened security risks.
Detailed Explanation:
In areas where there may be risks of terrorist attacks or explosions due to nearby high-risk facilities, implementing blast protection measures helps safeguard the data center's infrastructure. These measures can include reinforced walls, blast-resistant windows, and secure entryways designed to withstand explosive forces.
EPI Data Center Specialist References:
While not specifically mandated by ANSI/TIA-942, EPI training advises considering local risk factors, including proximity to potential targets, when evaluating the need for blast protection. This approach is aligned with risk assessment and mitigation practices to ensure facility security.
NEW QUESTION # 51
What is the first step in the design stage of the data center life cycle?
- A. Select vendors
- B. Do a design validation
- C. Freeze the design
- D. Define the scope of the project
Answer: D
Explanation:
The life cycle begins with planning and design. The very first step is to clearly define the project scope:
business requirements, capacity, availability targets, compliance standards, and budget. Without scope definition, design validation or vendor selection would be premature.
* Vendor selection (A) happens much later during procurement.
* Validation (B) occurs after conceptual and detailed designs are prepared.
* Freezing design (D) is the final stage before implementation.
Therefore, defining the project scope is the correct initial step.
References: ANSI/TIA-942-B Annex F (Lifecycle), ISO/IEC 30182 (Smart City & DC Lifecycle), PMI PMBOK (Scope Definition).
NEW QUESTION # 52
The 'maximum exposed area' of the fire-rated glass is defined by the supplier as 3 sqm/32 sqft. The window area is 4 sqm/43 sqft.
What would be the best option?
- A. Split the window into parts smaller than specified as the maximum exposed area and ensure fire-rated frames are used.
- B. Do not use fire-rated glass due to the size limit and replace it with normal glass.
- C. Split the window in two equal parts fitted together with transparent silicon glue.
- D. Split the window in two equal parts using an aluminum frame.
Answer: A
Explanation:
When the window area exceeds the maximum exposed area specified for fire-rated glass, it is necessary to split the window into sections that comply with the fire rating requirements. This means creating smaller sections that are each within the 3 sqm/32 sqft limit and using fire-rated frames to ensure that the entire assembly meets fire safety standards. This approach maintains the fire-rated integrity of the glass, while allowing for larger window areas.
Detailed Explanation:
Fire-rated glass is designed to contain fire and prevent it from spreading. If the window exceeds the maximum exposed area defined by the supplier, the integrity of the fire-rated glass could be compromised. By dividing the window into compliant sections with fire-rated frames, you ensure that each pane performs as intended in the event of a fire. Fire-rated frames help maintain the fire resistance across the entire assembly, making this option the best for safety and compliance.
EPI Data Center Specialist References:
EPI recommends adhering strictly to fire safety standards, especially when using materials like fire-rated glass. The guidelines emphasize that modifications should always respect the manufacturer's specifications to ensure the system remains effective in containing and preventing the spread of fire.
NEW QUESTION # 53
Management has requested a 15-minute battery bank assuming full load on the UPS. The UPS vendor has provided the following specifications of the UPS:
*Rated power: 30 kVA
*Rectifier input voltage: 400 V/3 phase
*Rectifier input power factor: 0.8
*Battery rated voltage: 384 V
*Number of cells: 192
*End of discharge voltage: 308 V
*Inverter output voltage: 400 V/3 phase
*Inverter output power factor: 0.8
What information is missing to perform the battery calculation?
- A. UPS efficiency
- B. Available battery charging current
- C. Inverter efficiency
- D. Load imbalance on the phases
Answer: A
Explanation:
To determine the required capacity of the battery bank for the 15-minute runtime at full load, one must know the total power requirement that the battery bank must supply. The specifications provided include most of the necessary details, such as rated power, input voltage, battery voltage, and discharge voltage. However, one critical piece of information is missing: the UPS efficiency.
Detailed Explanation:
In a data center UPS system, the battery bank is designed to supply power for a set duration when there is an input power failure. The UPS efficiency affects the actual power the UPS can deliver to the load compared to the power it draws from the batteries. The efficiency factor is necessary to accurately calculate the required capacity of the battery bank since it determines how much input power is needed from the batteries to supply the load at full capacity. The formula typically used to determine battery capacity involves factoring in UPS efficiency, as it allows you to understand the losses within the UPS system.
If UPS efficiency is not considered, there would be an inaccurate estimation of the actual power needed from the batteries. For instance, if a UPS has 90% efficiency, only 90% of the power drawn from the batteries reaches the load. Without knowing this efficiency, it is not possible to calculate the battery bank size accurately, as you cannot accurately estimate the losses within the UPS itself.
EPI Data Center Specialist References:
According to EPI Data Center Specialist training, understanding the UPS efficiency is essential for battery sizing. Without it, the calculations could lead to either undersizing or oversizing the battery bank, which affects both reliability and cost-effectiveness of the UPS system. The EPI Data Center Specialist course emphasizes that battery sizing must account for all losses within the UPS system, with efficiency being a primary factor in these calculations.
NEW QUESTION # 54
Which formula is correct?
- A. Phase-to-Neutral Voltage = (Phase-to-Phase voltage * 1.732) / Phase-to-Neutral Voltage
- B. Phase-to-Neutral Voltage = Phase-to-Phase voltage * 1.732
- C. Phase-to-Neutral Voltage = Phase-to-Neutral voltage * 1.732
- D. Phase-to-Neutral Voltage = Phase-to-Phase voltage /1.732
Answer: D
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 # 55
A computer room with raised floor and hot/cold aisles is designed. What is the minimum required distance between the air-conditioner outlet and the first rack?
- A. None
- B. 120 cm (4 ft)
- C. 60 cm (2 ft)
- D. 180 cm (6 ft)
Answer: B
Explanation:
To ensure uniform air distribution, there must be a buffer zone between CRAC/CRAH discharge and the first row of racks. Industry best practice (ASHRAE & TIA-942) specifies at least 1.2 m (4 ft).
* Less than 1.2 m risks air velocity hotspots and turbulence, disrupting cold aisle containment.
* More than 1.8 m wastes valuable floor space without added benefit.
Thus, 120 cm is the recommended minimum.
References: ANSI/TIA-942-B §6.5.3 (CRAC placement), ASHRAE TC 9.9 Thermal Guidelines.
NEW QUESTION # 56
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 change the 'S' factor of the formula to reflect the gas type used.
- B. Yes, as long as you take the difference between the net and gross volume into account.
- C. No, there is a significant difference in the formula for the different types of fire suppression gases.
- D. Yes, as long as you use the same units of measure, i.e., kg/m³ or lbs/ft³.
Answer: C
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 # 57
A battery bank has 800 Ah total capacity. How much charging current should the rectifier be able to supply?
- A. 80 A
- B. 60 A
- C. 40 A
- D. 160 A
Answer: A
Explanation:
Battery charging current is typically sized at 10% of the total Ah capacity to ensure safe charging without overheating.
Charging Current=800Ah×0.1=80A
* 40 A or 60 A would undercharge, extending recovery time after discharge.
* 160 A would be too high, causing heat and reducing battery life.
Thus, 80 A is correct.
References: IEEE Std 1188 (VRLA Battery Maintenance), IEC 60896-21/22 (Stationary Lead-Acid Batteries).
NEW QUESTION # 58
A data center scores Rated-3 in mechanical, Rated-4 in electrical, and Rated-2 in telecommunications. What is the overall rating?
- A. Depends on architectural rating
- B. Rated-4 since electrical is most important
- C. Rated-2
- D. Rated-4
Answer: C
Explanation:
ANSI/TIA-942 defines that the lowest rating across all four categories determines the overall facility rating. A facility cannot claim a higher overall level unless all subsystems meet or exceed that level.
In this case:
* Mechanical = Rated-3
* Electrical = Rated-4
* Telecommunications = Rated-2
Since telecommunications only meets Rated-2, the overall facility is Rated-2, regardless of higher scores elsewhere.
This ensures that weak areas (like cabling) are not ignored, because they can compromise overall availability.
References: ANSI/TIA-942-B §5.2.3 (Overall rating determination).
NEW QUESTION # 59
When designing a data center network, your company wants to minimize the number of network cables to install. 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. End of Row (EoR) design
- C. Star network design using coaxial cables
- D. Top of Rack (ToR) design
Answer: D
Explanation:
The Top-of-Rack (ToR) cabling layout places an access switch directly inside each rack. Each server in that rack only requires a short patch cable to connect to the switch, and only one or two uplinks per rack connect to aggregation switches. This greatly reduces the number of long horizontal cables across the data hall.
In contrast, an End-of-Row (EoR) design centralizes switches at the row end, requiring long horizontal cables from each server to the row cabinet. This can lead to thousands of extra copper or fiber runs in large deployments.
ANSI/TIA-942 and Cisco Design Guides emphasize that ToR is the best solution for minimizing cable bulk, improving airflow, and reducing cost in hyperscale or dense rack environments.
Thus, if the explicit design goal is to minimize cable quantity, ToR design is superior.
References: ANSI/TIA-942-B §8.2 (Cable Topologies: ToR, MoR, EoR), Cisco Data Center Access Layer Design Guide.
NEW QUESTION # 60
Smoke sensors need to be tested to ensure that they pick up a potential fire in the data center.
What should you recommend?
- A. Inject smoke at the floor level
- B. Test the sensors according to the vendor specification
- C. Test the sensors by injecting smoke or simulated smoke directly into the sensor
- D. Press the self-test button on each sensor in the data center
Answer: B
Explanation:
Testing smoke sensors should be conducted according to the vendor specifications to ensure compliance with safety standards and accurate results. Vendors provide specific testing procedures to account for the sensor type, environment, and operational characteristics, ensuring that tests do not damage the equipment or provide false results.
Detailed Explanation:
Smoke sensors can vary by type and sensitivity, so following the vendor's recommended testing procedure ensures the sensors function correctly without risking sensor damage. Injecting smoke or using a self-test might be insufficient or could lead to inaccurate assessments if they do not align with the vendor's testing protocol.
EPI Data Center Specialist References:
EPI recommends adhering to manufacturer specifications for testing critical safety equipment, ensuring that tests reflect real-world conditions without compromising sensor integrity or reliability.
NEW QUESTION # 61
What is the advantage or disadvantage of using MPO (Multi-fiber Push On)/pre-terminated fiber?
- A. It speeds up installation and provides an easy upgrade to transmission speeds up to 40 Gbit/s -100 Gbit/s.
- B. There is no advantage, as it cannot be used with OM4 optical fiber cables.
- C. It is a very flexible system as it can be used for both copper cables and optical fiber cables.
- D. There is no advantage, as it creates additional heat load in the data center.
Answer: A
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 # 62
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