CDCS Exin EXIN EPI Certified Data Centre Specialist Free Practice Exam Questions (2025 Updated)

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.

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.

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.

Network administration in structured cabling is governed by ANSI/TIA-606-B, which defines requirements for cable and asset administration, labeling, documentation, and record-keeping. It specifies how pathways, spaces, and cabling should be identified and labeled to ensure proper lifecycle management.

ANSI/TIA-568 covers cabling performance standards, not administration.

ISO/IEC 30129 relates to data center facilities and infrastructure but not cable management.

ASHRAE focuses on thermal management, not cabling.

Proper administration is critical in data centers because high cable density can lead to operational issues, troubleshooting delays, and risk of downtime if poorly managed. By enforcing labeling schemes, color codes, and database-driven records, ANSI/TIA-606 supports operational excellence and compliance with ANSI/TIA-942.

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.

The Open Compute Project (OCP), initiated by Facebook in 2011, focuses on open designs for servers, storage, racks, and power systems. The goals are:

Reduce energy consumption by using efficient hardware.

Save materials by eliminating unnecessary components.

Lower costs by standardizing and sharing open designs.

Option B is wrong—OCP hardware can be adopted by enterprises as well. Option C is unrelated (OCP is hardware, not OS). Option D is broader cloud adoption, not OCP’s direct mission.

Thus, the primary focus is energy, material, and cost savings through open-source hardware.

A spirit level bar should not be used for leveling a raised floor, as measurement errors are likely to propagate from one pedestal to the next. Spirit levels can introduce cumulative errors, leading to uneven floors, particularly in large installations where precise leveling is critical.

Detailed Explanation:

Using a laser level or a precision leveling device is recommended to ensure accuracy across all floor tiles. Spirit levels, while adequate for short spans, can transfer small inaccuracies from one pedestal to another, which can cause alignment issues and floor instability over time.

EPI Data Center Specialist References:

EPI data center guidelines discourage the use of spirit levels for raised floors. Instead, they advocate for precision tools like laser levels that ensure consistency and accuracy in large-scale installations, aligning with best practices for raised floor construction.

When installing overhead data cabling, it’s crucial to maintain minimum separation from power cables to prevent electromagnetic interference. Additionally, cabling should be arranged so that it does not obstruct fire detection and suppression systems, allowing for proper sensor function and suppression agent dispersion in the event of a fire.

Detailed Explanation:

Separation between power and data cabling minimizes the risk of interference and helps ensure compliance with standards for signal integrity. Proper placement relative to fire suppression systems ensures that any smoke or heat can be effectively detected, and suppression agents can be evenly distributed without obstruction from cabling.

EPI Data Center Specialist References:

EPI guidelines emphasize maintaining adequate separation between power and data cables for safety and performance and ensuring cabling does not interfere with essential safety systems in data centers.

LCC (Life Cycle Cost) is the metric that accounts for capital cost, operational energy, maintenance, and disposal/replacement. This holistic view is critical when evaluating cooling technologies like CRACs, CRAHs, chilled water, or free cooling systems.

HER (Heat Exchange Ratio) and COP (Coefficient of Performance) measure operational efficiency but not total lifecycle costs.

PUE measures overall data center efficiency but not specifically cooling CAPEX/OPEX.

Thus, LCC is the comprehensive metric that covers installation, operation, and disposal.

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.

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.

The cooling capacity of a raised floor tile is primarily influenced by the percentage of surface opening, the obstruction caused by the supporting construction, the pressure under the raised floor, and the damper construction. These factors dictate how much airflow can pass through the tile and how effectively cool air is distributed to the equipment in the data center.

Detailed Explanation:

The percentage of surface opening on a floor tile affects how much air can flow through, with larger openings allowing more airflow. Supporting structures beneath the floor can obstruct airflow, reducing cooling efficiency. Pressure under the raised floor impacts the velocity and volume of air that moves through the tile. Additionally, if dampers are installed, they control the airflow rate, which can be adjusted to meet specific cooling needs for the area.

EPI Data Center Specialist References:

EPI guidance on airflow management under raised floors emphasizes these factors as critical for effective cooling, especially in high-density areas. Ensuring unobstructed and adequate airflow helps maintain consistent cooling across equipment.

The minimum requirement for power feeds to a Rated-3 data center according to ANSI/TIA-942 is to have two independent power feeds, which can come from two different substations provided by the same power company. This ensures redundancy and concurrent maintainability, as each feed can support the load independently during maintenance or failure of the other.

Detailed Explanation:

The separation by two substations ensures resilience in case of a localized outage or substation maintenance, aligning with Rated-3 requirements for uninterrupted operation. ANSI/TIA-942 permits these feeds from a single utility provider as long as they are supplied from distinct substations.

EPI Data Center Specialist References:

EPI underscores the importance of dual power feeds from separate substations for Rated-3 facilities, highlighting that the ability to draw from different substations aligns with redundancy requirements for high availability.

Hypoxic air systems continuously reduce the oxygen concentration in the protected area to below the level required for combustion (typically 15–16%), while still remaining safe for human occupancy (>14%). By lowering oxygen concentration, ignition and flame propagation are prevented.

This is different from halocarbon or inert-gas clean agents, which flood the room only upon detection of fire. Hypoxic systems are preventive, creating a permanent fire-retardant environment.

They do not remove heat (A), fuel (C), or use water (D). Their key mechanism is oxygen displacement.

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.