CDCS Exam PDF [2026] Tests Free Updated Today with Correct 122 Questions
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NEW QUESTION # 20
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 a passive harmonic filter on the UPS
- B. Nothing, the UPS will be able to take care of the right levels of THDi
- C. Install an isolation transformer rated at K13 or K20
- 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 # 21
The electrical diagram of the data center shows the following UPS configuration and has a load of 80 kW.
What is the set-up in this data center?
- A. 2+N+1
- B. N+N(+1)
- C. (N+1)-(N+1)
- D. 2(N+1)
Answer: D
Explanation:
A 2(N+1) configuration implies two independent UPS systems, each with N+1 redundancy. This configuration provides high availability by ensuring that each UPS system can independently support the load with an additional unit for redundancy. Given the 80 kW load, this setup implies that two separate N+1 systems are running, providing reliability and fault tolerance for the data center's power needs.
Detailed Explanation:
The N+1 notation denotes that each system has one additional unit beyond what is needed to carry the load, providing redundancy. With 2(N+1), there are two such setups, ensuring that if one fails, the other can still support the load without interruption, fulfilling high availability requirements.
EPI Data Center Specialist References:
EPI teaches that multiple redundant systems, such as 2(N+1), enhance data center reliability by ensuring that power is maintained even if a failure occurs in one system. This meets the stringent demands for uptime in critical environments.
NEW QUESTION # 22
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 change the 'S' factor of the formula to reflect the gas type used.
- 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 take the difference between the net and gross volume into account.
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 # 23
A data center requires an audit for ANSI/TIA-942 Rated-3 compliance. Will the network architecture be part of this audit?
- A. Yes, amongst other aspects the network architecture should be Rated-3 compliant with ANSI/TIA-942
- B. No, only the type of cabling used will be audited
- C. No, as concurrent maintainability only applies to electrical and mechanical
- D. Yes, but only if network administration does not comply with ANSI/TIA-606
Answer: A
Explanation:
ANSI/TIA-942 defines ratings across four areas:
* Architectural
* Electrical
* Mechanical
* Telecommunications (network cabling + architecture)
A data center cannot be considered Rated-3 unless all four areas meet the concurrent maintainability criteria.
For telecom/networking, this means dual redundant backbone cabling, proper pathways, and separate routes to ensure no single point of failure.
* A and B are incorrect because they limit scope to electrical/mechanical or cabling only.
* C is incomplete: administration (ANSI/TIA-606) is part of compliance but architecture redundancy is mandatory.
References: ANSI/TIA-942-B §5.2 (Rated Levels), Annex E (Telecommunications infrastructure examples).
NEW QUESTION # 24
What should be implemented when an Inergen-based fire suppression system is installed in the computer room?
- A. Gas tanks need to be within or close to the data center
- B. Pressure release valves in the data center
- C. Proper water leak detection system
- D. Drainage system under raised floor
Answer: B
Explanation:
Inert gas systems (Inergen, Argonite, Nitrogen) extinguish fires by reducing oxygen concentration through massive gas discharge. This rapid release causes a significant pressure rise inside the room. To avoid structural damage to walls, ceilings, or raised floors, pressure relief vents (pressure release valves) must be installed.
* A (drainage) applies to water suppression.
* B (tank location) is logistical but not mandatory; remote storage with piping is acceptable.
* D (water leak detection) is unrelated to inert gas suppression.
Therefore, the critical safety requirement is pressure relief.
References: NFPA 2001 §5.2.1.2 (Pressure Relief), ISO 14520-1 §5.2.
NEW QUESTION # 25
A new network storage device in a non-standard size rack of approximately 600 kg/1,300 lbs is going to be installed in the data center.
Are new floor loading calculations required?
- A. No, as long as the equipment is less than 700 kg/1,500 lbs it will be within the limits.
- B. Yes, additional floor loading calculations need to be done by the floor manager, which should be verified by the safety engineer.
- C. Yes, a structural engineer, approved/endorsed by the building owner, should carry out new floor loading calculations.
- D. No, specifications of equipment brought into the data center will already be known during the design of the data center, and therefore the floor will be able to handle it.
Answer: C
Explanation:
For heavy equipment, such as a network storage device weighing approximately 600 kg/1,300 lbs, new floor loading calculations are indeed required, particularly since the rack is non-standard. A structural engineer, approved by the building owner, should conduct these calculations to ensure the floor can safely support the new load without risking structural integrity.
Detailed Explanation:
Data centers are designed with specific floor load ratings, which are determined during the design phase based on anticipated equipment. When adding or replacing equipment that is significantly heavy or non-standard, reassessing the floor's capacity is essential to avoid overloading. A structural engineer has the expertise to verify if the existing floor can accommodate the weight and, if not, can recommend reinforcement measures.
This step ensures compliance with safety standards and helps prevent damage to the infrastructure, which could lead to costly repairs or even catastrophic failure in extreme cases.
EPI Data Center Specialist References:
EPI Data Center Specialist training advises that any changes in the data center load, particularly involving non-standard and heavy equipment, warrant a structural assessment. Ensuring compliance with floor load capacity is a critical safety and operational concern, as underscoring data center infrastructure reliability and safety is a priority in EPI's best practices.
NEW QUESTION # 26
What is the main disadvantage of using a ToR (Top of Rack) design?
- A. A ToR (Top of Rack) switch has only optical interfaces.
- B. There will be more switches to manage.
- C. A single ToR (Top of Rack) switch is more expensive than an EoR (End of Row) switch.
- D. You need a separate rack to install all your ToR (Top of Rack) switches.
Answer: B
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 # 27
The air intake of the mission-critical server at the top of the rack is measuring 25 °C/77 °F.
Is this acceptable?
- A. As long as it does not exceed the average server room temperature of 38 °C/100 °F
- B. Yes, this is allowed according to the standards and guidelines
- C. Depends on the ANSI/TIA-942 Rating the data center needs to comply with
- D. No, the temperature needs to be 20 °C/68 °F
Answer: B
Explanation:
An air intake temperature of 25 °C (77 °F) at the top of the rack is acceptable according to data center standards and guidelines, such as those from ASHRAE. This temperature falls within the recommended range for inlet temperatures, which is typically between 18°C (64°F) and 27°C (81°F).
Detailed Explanation:
ASHRAE standards provide guidelines on acceptable temperature ranges for air intake in data centers to balance cooling efficiency and equipment safety. A temperature of 25°C is within the recommended operational range, allowing data centers to optimize energy efficiency while maintaining safe conditions for IT equipment.
EPI Data Center Specialist References:
EPI guidelines align with ASHRAE recommendations for server intake temperatures, confirming that 25°C is within acceptable limits for most mission-critical equipment. This ensures the data center maintains an efficient and reliable environment.
NEW QUESTION # 28
What is forced entry resistance based on?
- A. Rate and installed number of CCTV cameras
- B. Building materials used and the location of the data center
- C. Time, tools, and people
- D. The number of security guards on duty
Answer: C
Explanation:
Forced-entry ratings use defined attack tools and durations (time-to-breach) executed by attacker profiles.
References: EN 1627-1630 (Resistance Classes-tools and time), UL 972/UL 752 (attack tools/time).
NEW QUESTION # 29
A computer room needs to be fitted out with a gas-based fire suppression system. The computer room will be a high-density data center with about 30% of the racks being closed circuit cooling blade-center racks.
Should the supplier of the fire suppression system be informed on the design of the racks?
- A. Yes, the design of the racks has an influence on the fire suppression system design.
- B. Only when the racks might block access to the fire panel.
- C. No, cooling and design of racks have no influence on the fire suppression system design.
- D. Only when the rack height obstructs a potential fire suppression release point.
Answer: A
Explanation:
The design and configuration of racks, particularly high-density and closed-circuit cooling racks, directly impact the fire suppression system design. Closed-circuit cooling racks, like blade-center racks, can affect airflow and potentially trap heat, influencing how fire suppression agents are distributed within the space. Therefore, it is essential to inform the fire suppression system supplier about the rack design to ensure effective coverage and proper agent distribution.
Detailed Explanation:
High-density racks can change how smoke and heat travel, which in turn affects fire detection and suppression. Closed racks with built-in cooling can isolate airflow, requiring adjustments in fire suppression design to ensure that suppression agents reach all necessary areas, including within enclosed spaces. The supplier may need to account for these factors to ensure proper protection coverage.
EPI Data Center Specialist References:
The EPI Data Center Specialist training underscores that fire suppression systems must be tailored to the specific environmental characteristics of the data center. The design of racks, particularly high-density configurations, should always be considered to ensure that suppression agents can effectively control a fire, even in contained rack spaces.
NEW QUESTION # 30
Where should perforated tiles be installed?
- A. One tile per rack in front
- B. At the back of racks
- C. As close to AC as possible
- D. Every 5th rack
Answer: A
Explanation:
Perforated tiles should be located in front of equipment racks, aligned with cold aisles, to deliver supply air directly to server intakes. Best practice is one perforated tile per rack, adjusted based on airflow requirements and rack load.
* Placing tiles at the back (A) disrupts airflow.
* Spacing every 5th rack (B) provides insufficient cooling.
* Placing near AC (D) causes uneven distribution and pressure loss.
Thus, option C is correct.
References: ASHRAE TC 9.9 "Airflow Management," ANSI/TIA-942-B §6.5.
NEW QUESTION # 31
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 a passive harmonic filter on the UPS
- B. Nothing, the UPS will be able to take care of the right levels of THDi
- C. Install an isolation transformer rated at K13 or K20
- 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 # 32
Do you need to consider blast protection when designing a data center?
- A. Yes, blast protection is a requirement of ANSI/TIA-942.
- B. Yes, if the data center is a potential target or the building is located within the vicinity of (close by) a potential target.
- C. No, there is no reason for implementing blast protection as nobody can predict the impact of a bomb explosion.
- D. No, blast protection is not a requirement of ANSI/TIA-942.
Answer: B
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 # 33
How is the PUE ratio calculated?
- A. Total Facility Power ÷ Total ICT Equipment Power
- B. Total UPS Input Power ÷ Total UPS Output Power
- C. Total Air Conditioner Input Power ÷ Total Air Conditioner Output Power
- D. Total ICT Equipment Power ÷ Total Facility Power
Answer: A
Explanation:
PUE (Power Usage Effectiveness) is the most widely used metric to evaluate the energy efficiency of data centers. Defined by The Green Grid and adopted in ISO/IEC 30134-2, PUE is the ratio of the total facility power to the ICT (IT load) power.
Formula:
* Total Facility Power includes all electrical consumption: IT, cooling, lighting, power distribution losses, UPS inefficiency, etc.
* ICT Equipment Power is only the load drawn by servers, storage, and networking gear.
An ideal PUE is 1.0, meaning all power is used by ICT equipment with no overhead. Typical enterprise values are 1.5-2.0, while hyperscale operators target <1.2.
Other options are incorrect:
* B represents the inverse metric, known as DCiE (Data Center infrastructure Efficiency).
* C and D are partial subsystem efficiency metrics, not the global PUE.
References: ISO/IEC 30134-2 (KPIs - PUE), The Green Grid White Paper #49, ANSI/TIA-942-B §7.3.
NEW QUESTION # 34
The humidity in the computer room has increased from about 60% up to 85% Relative Humidity (RH). What potential risk does this pose to your equipment?
- A. The electrostatic discharge (ESD) levels will go up
- B. No risks at all
- C. There will be a cooling risk due to a high wet bulb temperature
- D. The risk of excessive wear and corrosion will increase
Answer: D
Explanation:
High relative humidity (above 80%) creates a serious risk for corrosion of electronic contacts, printed circuit boards (PCBs), and metallic components. Moisture in the air condenses more easily, especially when surfaces are cooler than ambient dew point. This can lead to oxidation of connectors, degradation of solder joints, and eventual failures in ICT hardware.
Electrostatic discharge (ESD) risks, by contrast, increase at low humidity (below 30%) because dry air promotes charge buildup. Therefore, option C is incorrect here. Similarly, option D (cooling risk from wet- bulb temperature) applies to evaporative cooling efficiency, not directly to ICT risk.
ASHRAE recommends data centers maintain RH between 40-60% for optimal reliability. Values above 80% RH are considered outside the recommended operating envelope and significantly increase the risk of corrosion, especially in the presence of airborne contaminants like sulfur dioxide (SO#) or hydrogen sulfide (H#S).
Therefore, the verified risk at 85% RH is corrosion-related degradation.
References: ASHRAE TC 9.9 Thermal Guidelines (2016 Edition, Table 4.1), IEC 60721-3-3 Environmental Conditions for ICT Equipment.
NEW QUESTION # 35
What should you consider when using raised floor tiles with air deflectors or louvers?
- A. Tiles with air deflectors or louvers can only be used to cool storage equipment.
- B. Tiles with air deflectors or louvers do not allow for a flexible cooling solution.
- C. Tiles with air deflectors or louvers can be very heavy.
- D. Tiles with air deflectors or louvers will reduce the cooling capacity of the tile.
Answer: C
Explanation:
Raised floor tiles with air deflectors or louvers are typically heavier than standard tiles due to the additional materials and mechanisms used to direct airflow. The added weight can pose challenges for installation and adjustment, and consideration must be given to the floor's load capacity and ease of maintenance.
Detailed Explanation:
Tiles with deflectors or louvers help direct airflow, enhancing cooling efficiency by focusing cool air where needed. However, these tiles are often heavier, which can affect handling and require reinforced raised floor systems. It's essential to factor in the weight for any floor tile replacements or installations to ensure they are compatible with the raised floor's structural capacity.
EPI Data Center Specialist References:
EPI data center design training mentions the potential impact of heavy tiles on floor handling and load capacity. Data center operators need to plan for safe handling and load-bearing capacity when using such specialized tiles.
NEW QUESTION # 36
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