Shielded twisted pair cables (STP) are Ethernet cables that feature additional protection against electromagnetic interference from external sources, such as radio waves, microwaves, or other network cables.
This is achieved by wrapping each pair of wires with a conductive shield, usually made of foil or braided wire, and then enclosing the entire cable with another shield layer. However, this shielding is not effective against low frequency electromagnetic fields (EMF) from power cables, which can induce currents and voltages in the network cables and cause signal distortion or data loss. Low frequency EMF can only be reduced by increasing the distance between the power and network cables, or by using a tre-foil cable arrangement, which is a special configuration of three power cables twisted together to cancel out the magnetic fields they generate.
References: STP Cable: Your Shield Against Network Disturbances; What is Shielded Twisted Pair Cable? - Advantages, Disadvantages; Shielded vs. Unshielded Cables: What's the Difference? - Cable Matters.

Block-level testing identifies weak or failing individual batteries that may not show up in string-level tests, enhancing overall system reliability.
References:
CDCP Exam Preparation Guide, Power/UPS Maintenance

The minimum clearance space required below water sprinkler heads and nozzles of gas-based fire suppression systems is 46 cm / 18 inches, according to the CDCP Preparation Guide1 and OSHA regulation 29 CFR
1910.159 (10)2. This clearance space is necessary to ensure that the sprinkler spray or gas discharge can reach the fire and cover the protected area effectively. Any material or obstruction below this clearance space can interfere with the sprinkler or gas distribution and reduce the fire suppression performance. Therefore, building owners and managers should ensure that all storage and objects in the data centre are kept below this clearance space, and that the clearance space is maintained at all times.
References:
1: CDCP Preparation Guide, page 24, section 2.4.3 2: Clarification of OSHA regulation 29 CFR 1910.159 (10), Sprinkler ...3, page 1, section 1

According to the IEEE definition, reliability is the ability of a system or component to perform its required functions under stated conditions for a specified period of time. Reliability is a measure of how often a system or component fails, and how long it takes to recover from a failure. Reliability is closely related to availability, which is the degree to which a system or component is operational and accessible when required for use. Reliability and availability are both affected by factors such as design, maintenance, testing, and environmental conditions.
References: EPI Data Centre Training Framework, CDCP Preparation Guide, Reliability engineering - Wikipedia

According to the CDCP® Preparation Guide, a natural disaster is a catastrophic event that is caused by natural forces and has a significant impact on human lives, property, and environment. Hurricanes are examples of natural disasters, as they are powerful storms that form over warm ocean waters and produce strong winds, heavy rain, storm surges, and flooding. Grid failure, blackouts, and human error are not natural disasters, but rather man-made or technological disasters that result from failures or errors in human systems or activities.
References: CDCP® Preparation Guide, page 9. Natural Disaster Readiness for Data Centers. EM-DAT - The international disaster database. PDC Global - Pacific Disaster Center.