Practice Free CDCS EXIN EPI Certified Data Centre Specialist Exam Questions Answers With Explanation

Battery sizing requires determining the real power demand of the UPS. With 30 kVA at 0.8 PF, the real load is 24 kW. To calculate required ampere-hours for 15 minutes of runtime, we need:

Where P = load, t = runtime, V = battery voltage, and ? = UPS efficiency.

Without UPS efficiency, we cannot know actual DC load on the batteries. A UPS with 90% efficiency will require more battery capacity than one with 95%. None of the other listed parameters (PF, imbalance, charging current) are critical for runtime capacity calculation.

With Halocarbon fire suppression systems, as the temperature increases, the amount of gas required for effective suppression decreases. This is because Halocarbon agents are stored as a liquid and discharge as a gas, expanding more at higher temperatures. As a result, less agent is needed at higher room temperatures to achieve the desired concentration for fire suppression.

Detailed Explanation:

Halocarbons rely on specific volumetric concentrations to suppress fires. Higher temperatures cause the agent to expand more rapidly, effectively filling the protected area with less agent needed to reach the required concentration. This is in contrast to some other gases, where temperature changes might not have the same effect on discharge quantities.

EPI Data Center Specialist References:

EPI data center training on fire suppression indicates that understanding the physical properties of agents like Halocarbons is key for correct system sizing. As the temperature rises, the gas expands more readily, thus requiring adjustments in the amount needed for effective coverage.

The most effective EMF mitigation is to install shielding as close as possible to the source of radiation. By blocking or redirecting magnetic flux at the origin (the transformer room walls), the overall field propagation into adjacent areas is minimized. If shielding were placed at the computer room, the field would already have spread over the intervening space, requiring more material and higher cost.

Standards such as IEEE Std 299 (EMC Shielding Effectiveness) and IEC 61000 emphasize source-based mitigation. Additionally, ANSI/TIA-942 requires EMF shielding where magnetic flux exceeds recommended ICT thresholds (generally <5 mG for sensitive tape/disk storage).

Although 100 mG is often tolerated by modern equipment, legacy magnetic storage can be affected, so shielding is still prudent. Hence, the correct location is at the transformer room wall.

Design changes during the implementation phase are generally allowed only when there is a strong business and/or technical justification. Changes at this stage can lead to delays, increased costs, or compromise design integrity. Thus, a rigorous assessment is required to ensure any modifications are essential and provide clear benefits or address critical issues.

Detailed Explanation:

Changes post-design freeze should be minimized to avoid scope creep and additional costs. However, if a technical issue arises that would affect operational goals, or a business need warrants modification, justified changes are permissible, following an impact assessment and approval process.

EPI Data Center Specialist References:

EPI project management guidelines recommend a controlled change management process during implementation, allowing changes only when they align with critical objectives or address unforeseen issues that affect the project's success.

According to ASHRAE TC 9.9 Thermal Guidelines (2016), the recommended intake temperature range for Class A1 ICT equipment is 18–27 °C (64–81 °F). The allowable lower limit is 15 °C (59 °F). Setting supply to 4 °C (39 °F) falls far below these limits.

Operating at such low temperatures would:

Cause condensation risk when surfaces drop below dew point.

Create severe energy inefficiency, as chillers would run at extremely low setpoints.

Possibly damage hardware due to thermal shock.

Options A and B are misleading—system capability or dew point alone does not override ASHRAE guidelines. Option D is incorrect since 20 °C is a common design target, not a requirement.

Thus, supplying 4 °C is not acceptable.

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.

Best practice is to begin raised-floor installation at the center of the room, working outward. This minimizes alignment errors and ensures the tile grid is centered, which is critical for aisle containment and rack alignment.

Starting at the perimeter (A, B, D) causes cutting of tiles along both sides, misalignment with rack rows, and possible airflow inefficiencies. By starting at the center, tiles can be cut symmetrically around the edges, providing better aesthetics, balanced airflow, and structural stability.

Industry guidelines such as CISCA recommend this approach for raised floors in mission-critical spaces.

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%.

For a Rated-3 data center, network architecture is indeed a key component of the audit under ANSI/TIA-942. This rating requires concurrent maintainability across all systems, including telecommunications infrastructure. The network architecture must therefore meet specific redundancy and reliability standards to ensure uninterrupted operations during maintenance or failure of any single component.

Detailed Explanation:

Rated-3 requirements extend beyond electrical and mechanical systems to include network architecture. This ensures that telecommunications systems are also designed for concurrent maintainability, thus contributing to overall uptime and resilience.

EPI Data Center Specialist References:

EPI endorses comprehensive assessments for Rated-3 facilities, emphasizing that network systems must meet standards for redundancy and concurrent maintainability, which align with ANSI/TIA-942’s holistic approach to data center reliability.

“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).

In seismic-prone areas, cables should be tightly secured to racks and cable trays to minimize movement during seismic activity. Properly securing the cables prevents them from being damaged due to excessive motion, which could lead to outages or damage to connected equipment.

Detailed Explanation:

Loose cables can be vulnerable to shaking or sudden jolts during an earthquake, increasing the risk of disconnection or damage. By tightly organizing and securing cables, you ensure they remain in place, even during significant movement, thereby maintaining connection integrity and reducing the risk of physical damage.

EPI Data Center Specialist References:

EPI training includes considerations for data centers in seismic zones, advising that cables be firmly anchored to support structures to reduce movement and mitigate potential damage during seismic events.

Forced-entry ratings use defined attack tools and durations (time-to-breach) executed by attacker profiles.

A Rated-4 facility requires dual active utility feeds, each from an independent substation, but they may come from the same utility provider if substations are geographically separate and independent.

Option A is too strict; ANSI/TIA-942 does not mandate two different companies.

Options C and D do not provide true independence and would fail Rated-4 requirements.

Thus, the minimum is two substations, possibly same provider.

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.

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.

Data centers typically have high airflow environments due to CRAC/CRAH units, containment, and raised floors. Standard smoke detectors (ionization or photoelectric) often fail to detect incipient smoke because the air movement disperses particles.

The correct solution is VESDA/VIEW (Very Early Warning) smoke detection systems, which use aspirating smoke detectors (ASD). These systems continuously sample air through pipes and can detect smoke particles at concentrations as low as 0.001% obscuration/m. This provides early detection well before fire growth, allowing mitigation without system shutdown.

Dry pipe sprinklers (A) are suppression, not detection.

Ionization detectors (B) are sensitive to flaming fires but unreliable in high-airflow environments.

Photoelectric detectors (C) are better for smoldering fires but still inadequate in high airflow compared to ASD systems.

Commissioning occurs during the Implementation stage of the data center life cycle. This phase involves the final testing and verification of systems and equipment to ensure they meet design specifications and operational requirements before the data center goes live.

Detailed Explanation:

The Implement phase includes activities such as installation, configuration, and testing. Commissioning is a crucial step that validates the performance and reliability of all critical systems, including power, cooling, and network infrastructure, to ensure they operate as intended under various conditions. Proper commissioning helps identify and resolve any issues before the data center becomes fully operational.

EPI Data Center Specialist References:

EPI training emphasizes that commissioning is essential for verifying that the data center meets design and performance criteria, aligning with best practices in data center project management to minimize risks and ensure readiness for operation.

As relative humidity decreases, Electrostatic Discharge (ESD) risks increase. Lower humidity levels reduce the amount of moisture in the air, which normally helps dissipate static charges. When the humidity drops from 50% to 35%, the likelihood of static electricity accumulating on surfaces rises, leading to a higher potential for ESD incidents that could damage sensitive IT equipment.

Detailed Explanation:

ESD events are more common in dry environments because there is less atmospheric moisture to neutralize electrical charges. Maintaining relative humidity above 40% helps minimize the risk of ESD, which is why data centers often control humidity levels tightly to protect equipment from static discharge that could cause hardware failures or data loss.

EPI Data Center Specialist References:

EPI data center best practices stress the importance of maintaining stable humidity levels to prevent ESD, particularly in computer rooms. Recommended humidity ranges are typically above 40% to prevent conditions that would foster static buildup.

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.

In areas with frequent and extended power outages, continuous generators with at least an N+1 configuration are necessary to ensure consistent power availability. Continuous generators are designed for prolonged operation, making them suitable for scenarios where utility power is frequently unavailable, as in this case with outages exceeding 650 hours per year. An N+1 configuration ensures redundancy, which is critical for maintaining uptime in a high-availability data center.

Detailed Explanation:

Continuous generators provide reliable power over long durations, unlike standby generators, which are intended only for short-term use. The N+1 configuration ensures that there is always an additional generator available in case of failure, thus maintaining power supply even if one generator goes offline.

EPI Data Center Specialist References:

EPI best practices recommend continuous generators with redundancy for data centers located in areas with high power instability to maintain reliability and continuous operation.

The server’s repeated overheating despite adequate intake and exhaust temperatures suggests that dust buildup inside the server may be impeding heat transfer. Dust accumulation can obstruct airflow within the server, insulate components, and disrupt the convection-based cooling systems that regulate internal temperatures, leading to overheating and potential hardware failures.

Detailed Explanation:

While the intake and exhaust temperatures appear within acceptable ranges, internal dust can reduce airflow and impede cooling efficiency, causing internal components to overheat despite seemingly normal ambient conditions. Regular cleaning and maintenance are critical for preventing dust-related issues, especially in high-powered equipment like a 5kW server.

EPI Data Center Specialist References:

EPI emphasizes regular maintenance to prevent dust buildup in data center equipment. Dust can significantly impact cooling efficiency and lead to overheating, which underlines the importance of routine cleaning for optimal server performance.

OM5 is optimized for Short Wavelength Division Multiplexing (SWDM) between 850–953 nm. This allows transmission of multiple wavelengths over a single fiber pair, reducing the number of fibers required for high-speed links.

OM4 already supports 100 GbE to 150 m, but OM5 with SWDM extends reach and reduces cabling bulk.

Option B is false because OM5 offers distinct SWDM benefits.

Option C is incorrect—OM5 is laser-optimized, not LED-based.

Option D is misleading; OM5 doesn’t extend 100 GbE to 500 m (that requires single-mode OS2 fiber).

Thus, the key advantage is SWDM support.

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.

To calculate the cooling airflow requirement for ICT equipment, you can use the formula:

CFM=Power (kW)×3160?T(°F)\text{CFM} = \frac{\text{Power (kW)} \times 3160}{\Delta T (\text{°F})}CFM=?T(°F)Power (kW)×3160?

For equipment consuming 6 kW with a Delta-T of 20°F:

CFM=6×316020=948?1,000?CFM\text{CFM} = \frac{6 \times 3160}{20} = 948 \approx 1,000 \, \text{CFM}CFM=206×3160?=948?1,000CFM

Detailed Explanation:

This formula provides an estimate of the cubic feet per minute (CFM) of air required to cool the equipment based on its power consumption and the temperature difference (Delta-T) between intake and exhaust. The Delta-T represents the cooling effectiveness of the airflow.

EPI Data Center Specialist References:

EPI recommends using this calculation for determining airflow requirements in data centers, ensuring that cooling systems are adequately sized to maintain equipment within safe temperature limits.

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.

The data center life cycle is typically divided into four stages:

Design (scope, architecture, planning)

Implement (construction, installation, testing & commissioning)

Operate/Optimize (day-to-day operations, maintenance, continuous improvement)

Retire (decommissioning and migration)

Testing and commissioning occur in the Implement stage, after construction but before handover. This includes Integrated Systems Testing (IST), which validates that all systems (electrical, cooling, fire protection, telecom) perform to design intent and redundancy requirements.

Without commissioning, the data center cannot be certified or considered operational.

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:

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Options A and B are incomplete, while option C is an experimental method, not standard practice. The recognized method is option D.

For an MCB (Miniature Circuit Breaker) in the PDU of an air-conditioning unit, a C-Curve is recommended. C-Curve breakers are suitable for circuits with moderate inrush currents, such as those experienced in air conditioning units. They provide protection against overloads while accommodating the inrush without nuisance tripping.

Detailed Explanation:

C-Curve breakers trip when currents exceed 5 to 10 times the rated current, making them ideal for devices like air conditioners that experience moderate inrush currents upon startup. This characteristic provides a balance between protection and resilience against startup surges, preventing unnecessary trips while safeguarding the circuit.

EPI Data Center Specialist References:

EPI guidance for data center electrical systems specifies that C-Curve breakers are appropriate for equipment with inrush characteristics similar to air conditioning units, as they help prevent operational interruptions caused by typical surges during equipment start-up.

MCBs (Miniature Circuit Breakers) are characterized by their tripping curves:

B-Curve: Trips at 3–5 × rated current; suitable for resistive loads.

C-Curve: Trips at 5–10 × rated current; suitable for mixed loads including ICT equipment with moderate inrush current.

D-Curve: Trips at 10–20 × rated current; used for heavy inductive loads like motors.

A-Curve: Very sensitive, rarely used outside specialty electronics.

Since ICT equipment like servers and network devices have moderate inrush currents (from power supplies), the recommended breaker is C-Curve. It balances protection against nuisance tripping while still ensuring fault clearance.

MPO connectors are multi-fiber connectors that support 12, 24, or more fibers in a single connector. Their key advantage is enabling parallel optics—where multiple fibers transmit simultaneously. This makes them ideal for 40GBASE-SR4 and 100GBASE-SR10 Ethernet links.

With OM4 or OM5 fiber, MPO cabling supports short-reach high-speed links in modern data centers.

Option A is incorrect; MPO works with OM3/OM4/OM5.

Option C is misleading; all connectors degrade with repeated use.

Option D is false because MPO is optical-only.

The real advantage is parallel multi-fiber transmission in one connector, simplifying cabling for high-speed networking.

NFPA 75 (IT equipment rooms) recommends pre-action sprinklers for data processing spaces to minimize accidental water discharge risk; wet-pipe is generally discouraged directly over IT hardware.