Exin CDCS Practice Exam Questions & Answers

Attenuation is the logarithmic ratio between input and output signals. For power, we use 10 log; for voltage or current, 20 log. Since EMF shielding is measured as field strength (V/m or A/m), power relationship is proportional to the square of field. Thus the correct attenuation calculation for shielding effectiveness is:

where:

M = maximum permissible field strength

R = measured field strength after shielding

This ensures the shield reduces field intensity to below allowable 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 Reference:

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 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 Reference:

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.

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).

D is false.

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 18C (64F) and 27C (81F).

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 25C is within the recommended operational range, allowing data centers to optimize energy efficiency while maintaining safe conditions for IT equipment.

EPI Data Center Specialist Reference:

EPI guidelines align with ASHRAE recommendations for server intake temperatures, confirming that 25C is within acceptable limits for most mission-critical equipment. This ensures the data center maintains an efficient and reliable environment.