N10-009 Question 184
Single answerPower: Uninterruptible power supply (UPS), Power distribution unit (PDU), Power load, VoltageA network administrator is installing a new rack of equipment in a small server room. The rack will contain a firewall, two PoE switches, and several WAN edge devices. During planning, the administrator sees that the combined load of the devices is close to the current UPS's maximum rated output. The administrator also wants all devices to stay online long enough for graceful shutdown during a utility power failure. Which action is the BEST next step before connecting the equipment?
- A
Connect all devices to the existing UPS and use the rack PDU to distribute power evenly across its outlets
- B
Replace the UPS with a model that has sufficient voltage and watt/VA capacity for the expected load and required runtime
- C
Increase runtime by plugging the UPS into a standard surge protector and then into the wall outlet
- D
Use a basic PDU instead of a UPS, because the PDU can balance power load and prevent outages
Show answer and explanation
Correct answer: B
Explanation
The best answer is to replace the UPS with one that is properly sized for the expected load and required runtime. In rack environments, a UPS and a PDU serve different roles: the UPS provides battery backup and often voltage regulation or conditioning, while the PDU distributes power to multiple devices in the rack. When planning power, administrators should verify voltage compatibility with the equipment and ensure the UPS output rating in watts/VA exceeds the actual power load with reasonable headroom. They should also confirm the runtime at that load meets operational needs, such as allowing systems to remain online briefly or shut down gracefully. This aligns with common vendor and data center best practices from UPS manufacturers such as APC/Schneider Electric, Eaton, and Vertiv, which emphasize proper load calculation, avoiding overload, and not connecting UPS units through surge strips or daisy-chained devices.
- A. Incorrect.
This is incorrect. A PDU distributes power to multiple devices in a rack, but it does not increase the UPS's available output capacity or runtime. If the connected equipment load is already close to the UPS maximum, simply spreading devices across PDU outlets does not reduce total load. This option reflects a common misconception that a PDU manages or expands UPS power capacity.
- B. Correct.
This is correct. The administrator should verify that the UPS is sized appropriately for the environment by checking both input/output voltage compatibility and output capacity in watts or VA, along with estimated runtime at the intended load. If the current UPS is near its limit, replacing it with a properly sized unit is the best step to avoid overload conditions and to provide enough battery time for graceful shutdown. In real deployments, UPS sizing should account for current load, startup/inrush considerations where applicable, and desired runtime.
- C. Incorrect.
This is incorrect. A UPS should be connected directly to an appropriate wall receptacle as specified by the manufacturer, not daisy-chained through a surge protector or power strip. Doing so can create safety issues, interfere with UPS operation, and violate vendor installation guidance. It also does not meaningfully increase runtime or power capacity.
- D. Incorrect.
This is incorrect. A basic PDU only distributes incoming power to multiple outlets; it does not provide battery backup, voltage regulation, or ride-through during power loss. While some intelligent PDUs can monitor load, they still do not replace the function of a UPS. This option confuses power distribution with backup power protection.