CDCP General 5 — Questions and Answers
Question 1: What is the primary purpose of a static transfer switch (STS) in a data center power infrastructure?
- To convert AC power to DC power for servers
- To switch a load between two independent power sources with minimal interruption (Correct answer)
- To regulate voltage output from a UPS
- To distribute power from a PDU to individual circuits
Correct answer: To switch a load between two independent power sources with minimal interruption
An STS automatically transfers a load between two independent power feeds in less than a quarter cycle, ensuring high availability.
Question 2: Which data center design principle does 'concurrent maintainability' describe?
- The ability to perform planned maintenance without shutting down the IT load (Correct answer)
- Simultaneous maintenance performed by multiple technicians
- Maintenance scheduled during low-traffic periods only
- Remote maintenance performed without on-site personnel
Correct answer: The ability to perform planned maintenance without shutting down the IT load
Concurrent maintainability means any component can be serviced, repaired, or replaced while the facility continues to support its full IT load.
Question 3: In data center power distribution, what does a 'dual-corded' server configuration provide?
- Higher voltage operation for efficiency
- Two independent power paths from separate circuits to the same server (Correct answer)
- A primary and a monitoring network connection
- Doubled CPU power for high-performance computing
Correct answer: Two independent power paths from separate circuits to the same server
Dual-corded servers connect to two independent power circuits or PDUs, eliminating a single point of failure at the server level.
Question 4: What environmental monitoring parameter is most critical for detecting water-related risks in a data center?
- Differential air pressure
- Leak detection sensors (Correct answer)
- Particulate matter sensors
- Electromagnetic interference (EMI) levels
Correct answer: Leak detection sensors
Leak detection sensors placed under raised floors and near cooling equipment provide early warning of water leaks before equipment damage occurs.
Question 5: What is the function of a Power Distribution Unit (PDU) in a data center rack?
- To convert high-voltage AC from the UPS into low-voltage DC for servers
- To distribute power from a central source to multiple individual devices within a rack (Correct answer)
- To measure the carbon footprint of rack-level power consumption
- To provide battery backup power for individual rack equipment
Correct answer: To distribute power from a central source to multiple individual devices within a rack
A rack PDU receives power from a branch circuit and distributes it through multiple outlets to servers and equipment within the rack.
Question 6: Which security access control method uses biometric data combined with a PIN or card as a second factor for data center entry?
- Single-factor authentication
- Two-factor authentication (2FA) (Correct answer)
- Role-based access control (RBAC)
- Discretionary access control (DAC)
Correct answer: Two-factor authentication (2FA)
Two-factor authentication combines something you have or are (biometric/card) with something you know (PIN), greatly strengthening physical access security.
Question 7: What is the recommended maximum relative humidity level in a data center to prevent electrostatic discharge (ESD) risks?
- Below 20%
- 20–80% (non-condensing) (Correct answer)
- Above 90%
- Exactly 50% at all times
Correct answer: 20–80% (non-condensing)
ASHRAE recommends maintaining relative humidity between 20% and 80% non-condensing to balance ESD risk (too dry) and condensation risk (too humid).
CDCP General 5
What is the primary purpose of a static transfer switch (STS) in a data center power infrastructure?