[Jun-2026] Latest EXIN CDCS Certification Practice Test Questions
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EXIN CDCS Exam Syllabus Topics:
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NEW QUESTION # 15
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. No, there is a significant difference in the formula for the different types of fire suppression gases.
- B. Yes, as long as you take the difference between the net and gross volume into account.
- C. Yes, as long as you use the same units of measure, i.e., kg/m³ or lbs/ft³.
- D. Yes, as long as you change the 'S' factor of the formula to reflect the gas type used.
Answer: A
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 # 16
What indicates the breaking capacity of a fuse or breaker?
- A. The current at which the device will trip.
- B. The current that a fuse or breaker is able to interrupt without being destroyed or causing an electric damaging arc.
- C. Mechanical strength of the casing of a fuse or breaker.
- D. 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.
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 # 17
Do you need to consider bullet (ballistic) protection when designing a data center?
- A. No; bullet protection is not a requirement of ANSI/TIA-942
- B. No, there is no reason for implementing bullet protection as you cannot predict the type of weapons that might be used
- C. Yes, bullet protection is a requirement of ANSI/TIA-942 for Rated-3/4 data centers
- D. Yes, but only when the data center is built in an area with a high criminality rate or with a risk of terrorist attacks
Answer: D
Explanation:
ANSI/TIA-942 requires a risk assessment-based approach to physical security; ballistic protection is not mandated but may be justified by threat analysis.
* A is incomplete (it may still be required by risk).
References: ANSI/TIA-942-B §6.4 Physical Security (threat/risk assessment), ISO 31000 (risk management).
NEW QUESTION # 18
What is the preferred way to measure dust levels in the computer room?
- A. By taking dust samples under the raised floor
- B. With an air particle hand-held analyzer
- C. By opening up equipment for inspection
- D. With test coupons
Answer: D
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 # 19
What is the effect of having a damper (in open position) construction in a raised-floor tile?
- A. Dampers increase the air volume by approximately 10%
- B. Dampers allow for a higher supply air temperature
- C. Dampers can be used when there is a high rate of temperature change in the computer room
- D. Dampers reduce the air volume by approximately 10%
Answer: D
Explanation:
Perforated tiles with integrated dampers are common in raised-floor data centers because they allow airflow regulation at the rack level. However, even when the damper is fully open, the mechanism inside the tile restricts airflow. This typically reduces the delivered airflow by around 10% compared to a non-dampered tile of the same type.
* Option A is incorrect because dampers do not affect supply temperature; they only throttle volume.
* Option B is wrong since dampers cannot increase volume-they only add resistance.
* Option D is partially true that dampers help with temperature balancing, but the main effect (in open position) is volume reduction.
Thus, the technical impact of dampers in open position is a slight airflow reduction, usually quantified as
~10%.
References: ASHRAE TC 9.9 - "Airflow Management in Raised-Floor Environments," ANSI/TIA-942-B §6.
5 (Cooling Infrastructure).
NEW QUESTION # 20
When shielding material reaches its saturation point, what will be the impact?
- A. The shielding material will reach its maximum electrically charged state.
- B. The shielding material will no longer be able to attenuate (reduce) additional EMF.
- C. The shielding material will increase its permeability factor.
- D. The shielding material will reach its optimal shielding performance state.
Answer: B
Explanation:
When shielding material reaches its saturation point, it can no longer effectively attenuate additional EMF. At saturation, the material's ability to absorb or redirect magnetic fields is exhausted, meaning it cannot provide further shielding beyond this point. Additional EMF exposure would pass through the material without significant reduction.
Detailed Explanation:
Saturation occurs when the material's magnetic domains are fully aligned with the magnetic field, leaving no capacity to absorb or deflect further EMF. This can happen with high EMF levels, beyond the material's design limits, resulting in a breakdown of shielding effectiveness.
EPI Data Center Specialist References:
EPI guidelines on EMF management indicate that selecting appropriate shielding materials with sufficient capacity is essential to prevent saturation and ensure continuous protection. Saturation limits should be considered during design to avoid compromised shielding performance.
NEW QUESTION # 21
You need to determine the strategy for the cooling audit. All the servers are based on a front-to-rear (F-R) airflow design.
Which location for the temperature/humidity measurement should you recommend for the audit?
- A. At 1.5 meters/5 feet above the floor in the middle of the hot aisle
- B. At the front/intake of the server at 50 mm/2 inch
- C. At 1.5 meters/5 feet above the floor in the middle of the cold aisle
- D. At the back/rear of the server at 50 mm/2 inch
Answer: B
Explanation:
For a cooling audit in a data center, it is essential to measure temperature and humidity where air enters the servers to accurately assess cooling performance. In this case, since all servers have a front-to-rear (F-R) airflow design, measuring at the front/intake of the server will provide a precise understanding of the cooling conditions that the equipment is experiencing.
Detailed Explanation:
Servers with a front-to-rear airflow design draw in cool air from the cold aisle at the front, which is then exhausted into the hot aisle at the rear. By measuring temperature and humidity 50 mm/2 inches from the front intake, you gather data on the air conditions right before it enters the servers, providing an accurate representation of the cooling environment as it directly impacts the equipment.
Measuring in the cold aisle at the front intake ensures that the readings reflect the actual conditions of the incoming air that the servers depend on for effective cooling. This approach is consistent with best practices for maintaining thermal conditions in a data center, as it helps confirm that the cooling systems are delivering air within the required temperature and humidity specifications.
EPI Data Center Specialist References:
According to the EPI Data Center Specialist curriculum, the optimal placement for temperature and humidity sensors is at the intake of the equipment in the cold aisle, as it directly correlates to the environmental conditions affecting the servers. This positioning allows for a more effective audit of cooling performance, which is critical for maintaining the reliability and efficiency of the data center's operations.
NEW QUESTION # 22
What indicates the overcurrent of a fuse or breaker?
- A. The maximum inrush current an overcurrent protection device can handle within a defined period of time
- B. The maximum electrical current which can flow in a particular electrical system under short-circuit conditions; it is determined by the voltage and impedance of the supply system
- C. The current that a fuse or breaker is able to interrupt without being destroyed or causing an electrically damaging arc
- D. The current at which the device will trip
Answer: D
Explanation:
"Overcurrent" for protective devices is the condition above the device's rated/trip value that causes operation (tripping/melting).
* A = inrush tolerance, not the definition of overcurrent.
* B = prospective short-circuit current (Ik).
References: IEC 60947-2 (LV circuit breakers, defs 2.5.13 Overcurrent; 2.3.3 Rated short-circuit breaking capacity), IEC 60269 (fuses).
NEW QUESTION # 23
An air-conditioner unit needs to be selected. Two types are available:
Unit-A has a Sensible Heat Ratio (SHR) of 0.7.
Unit-B has a Sensible Heat Ratio (SHR) of 0.9.
From an efficiency point of view, which one should be selected?
- A. It does not matter, as the Sensible Heat Ratio has nothing to do with efficiency.
- B. Not relevant, as Sensible Heat Ratio is only specified for air-conditioner equipment to indicate the ratio between intake temperature and exhaust temperature.
- C. Unit A
- D. Unit B
Answer: D
Explanation:
From an efficiency standpoint, Unit B with a Sensible Heat Ratio (SHR) of 0.9 is preferable. A higher SHR indicates that a greater proportion of the air conditioner's capacity is dedicated to sensible cooling (temperature reduction) rather than latent cooling (moisture removal). In data centers, sensible cooling is more critical since IT equipment primarily generates heat without adding significant moisture.
Detailed Explanation:
An SHR of 0.9 means that 90% of the cooling capacity is used for sensible cooling, which is more efficient for environments like data centers where humidity control is typically less of a concern. Opting for an air conditioner with a higher SHR ensures that most of the cooling energy is focused on temperature reduction, making Unit B more efficient in this scenario.
EPI Data Center Specialist References:
EPI data center best practices recommend choosing cooling units with higher SHR values in data centers, as they better match the cooling needs of IT equipment. High SHR units improve cooling efficiency by concentrating on sensible heat removal, which is vital for maintaining the optimal thermal environment.
NEW QUESTION # 24
ICT rack consumes 3 kW with #T ~11 °C (20 °F). Calculate required airflow (CFM).
- A. ~500 CFM
- B. ~1,500 CFM
- C. ~1,000 CFM
- D. ~160 CFM
Answer: A
Explanation:
Cooling airflow (CFM) can be calculated from:
Where P = IT load.
So approximately 500 CFM is required.
* 1,500 and 1,000 CFM are too high.
* 160 CFM is far too low.
Therefore, the correct answer is ~500 CFM.
References: ASHRAE TC 9.9 (Cooling Calculations), ANSI/TIA-942-B §6.5.
NEW QUESTION # 25
When are the wet bulb and dry bulb temperatures identical?
- A. When the relative humidity is 100%
- B. When the dry bulb's temperature is at the lowest allowable temperature for IT equipment as per ASHRAE
- C. When the relative humidity is at the best practice value for relative humidity, being 50% RH
- D. When the dry bulb's temperature is at the highest allowable temperature for IT equipment as per ASHRAE
Answer: A
Explanation:
The wet bulb and dry bulb temperatures become identical when the relative humidity reaches 100%. At this point, the air is fully saturated with moisture, meaning it can no longer absorb additional water vapor. As a result, the rate of evaporation decreases, and there is no difference between the dry bulb and wet bulb temperatures.
Detailed Explanation:
The dry bulb temperature measures the air temperature, while the wet bulb temperature takes into account the cooling effect of evaporation. When relative humidity is at 100%, the air has reached its saturation point, and no further evaporation occurs. This causes both the wet bulb and dry bulb thermometers to display the same temperature reading. This condition is critical in understanding environmental conditions, particularly in HVAC and data center environments, where humidity control is essential to avoid equipment overheating or corrosion.
EPI Data Center Specialist References:
The EPI Data Center Specialist training includes understanding humidity levels and their impact on data center environments. Knowing when wet bulb and dry bulb temperatures align helps data center operators manage moisture levels effectively, which is essential for preventing issues related to high humidity, such as condensation on IT equipment.
NEW QUESTION # 26
You are working on the design of a new facility. The electrical riser of the building with high current power is located close to the area where sensitive IT equipment in the computer room will be located.
What should you recommend to reduce the amount of EMF coming from the electrical riser?
- A. Install single-phase power cabling
- B. Install three-phase power cabling based on a combined cable (e.g. XLPE etc.)
- C. Install bus bar trunking
- D. Install three-phase power cabling based on three individual core wires
Answer: B
Explanation:
To reduce Electromagnetic Fields (EMF) emanating from the electrical riser near sensitive IT equipment, three-phase power cabling in a combined cable (such as XLPE) is effective. Combined cabling helps reduce EMF by keeping the conductors tightly packed, which minimizes magnetic fields generated by current flow.
Cables like XLPE (cross-linked polyethylene) also offer better insulation, which helps mitigate EMF interference with nearby IT equipment.
Detailed Explanation:
Using a combined three-phase cable reduces EMF because the magnetic fields generated by each phase tend to cancel each other out when in close proximity. This arrangement helps reduce the overall magnetic field strength. In addition, XLPE and similar materials provide good insulation, making them a preferred choice for reducing EMF emissions around sensitive equipment.
EPI Data Center Specialist References:
EPI data center best practices recommend mitigating EMF interference through combined cabling arrangements, especially near areas where sensitive IT equipment is located. Reducing EMF is crucial to maintaining equipment reliability and ensuring compliance with safety standards.
NEW QUESTION # 27
What is the main disadvantage of using a ToR (Top of Rack) design?
- A. There will be more switches to manage.
- B. A single ToR (Top of Rack) switch is more expensive than an EoR (End of Row) switch.
- C. A ToR (Top of Rack) switch has only optical interfaces.
- D. You need a separate rack to install all your ToR (Top of Rack) switches.
Answer: A
Explanation:
A Top of Rack (ToR) design typically requires more switches because each rack has its own switch to manage network connections, as opposed to End of Row (EoR) or centralized designs, which consolidate switches. While ToR designs improve cabling efficiency and reduce latency, they also increase the number of switches, thus raising management complexity and potentially increasing capital and operational costs.
Detailed Explanation:
In a ToR setup, each rack's individual switch allows for quick access and streamlined cabling within the rack. However, this setup means more devices to configure, monitor, and maintain, which can increase administrative overhead and network management complexity.
EPI Data Center Specialist References:
EPI documentation notes that ToR designs can improve performance but also lead to increased management needs due to the higher switch count, making them less ideal in environments where simplified network management is prioritized.
NEW QUESTION # 28
A data center is in an area where utility power is highly available-only a few outages per year, typically <1 hour per event and <50 hours/year not available. What type of generators should be installed?
- A. Continuous generators in at least N+1
- B. Standby generators; no N+1 needed as the risk of a failure to start is negligible
- C. Standby generators, ideally in an N+1 configuration
- D. A combination of standby, prime, and continuous sized to 500% of the load
Answer: C
Explanation:
With infrequent/short outages, Standby (Emergency Standby Power, ESP) generators are appropriate; N+1 mitigates failure-to-start risk and supports concurrently maintainable designs.
References: ISO 8528-1 (generator rating definitions: ESP/PRP/Continuous), ANSI/TIA-942-B §6.2 (electrical redundancy).
NEW QUESTION # 29
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. At all times, the levels should allow for security cameras to function properly.
- B. Security guards should perform regular inspections verifying the system works.
- C. It is not advisable to use such a system since it will reduce the lifetime of LED lighting.
- D. The system should not be based on motion detection as the lights might suddenly switch off while staff is still at work.
Answer: A
NEW QUESTION # 30
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. EoR (End of Row) design
- B. It does not matter as the number of switches is not influenced by the physical cabling layout
- C. Star network design using coaxial cables
- D. ToR (Top of Rack) design
Answer: A
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 # 31
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