問83
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PoEの説明として, 適切なものはどれか。
平成31年度 春期 ITパスポート試験 問83
テクノロジ系ネットワーク › ネットワーク方式
This question's explanation and your answers so far.
解説
問 83
- ア
正解 PoE (Power over Ethernet) is a technology that uses the Ethernet LAN cable to supply power at the same time as data communication. Choice ア states exactly that it “supplies power using LAN cables” and is “used in cases such as installing a wireless LAN access point in a location without a power outlet,” correctly describing the definition and use of PoE, so it is the correct answer. When installing a wireless LAN access point or an IP camera on a ceiling or wall where power is hard to obtain, being able to supply power through a single LAN cable without electrical wiring work is a representative advantage of PoE.
Incorrectイ
A technology that uses existing electrical wiring (power lines) as a communication path to build a LAN is a description of PLC (Power Line Communication), not PoE. PoE is a technology that sends power over a LAN cable, whereas PLC conversely sends data over power lines — the two are opposite in direction.
Incorrectウ
A technology that mutually converts and forwards between global addresses and private addresses and is used at the boundary between an internal LAN and the Internet is a description of NAT (Network Address Translation, or NAPT), and is unrelated to PoE.
Incorrectエ
A technology that automatically negotiates the communication speed and communication mode (full-duplex/half-duplex) with the communication partner is a description of auto-negotiation, which is a separate thing from PoE and has nothing to do with the power-supply function.
ここがポイント
- PoE (Power over Ethernet) = a technology that performs communication and power supply simultaneously over a LAN cable. Used for installing wireless LAN access points or IP cameras in locations without a power source.
- Distinguishing confusingly similar technologies: PLC = data communication over power lines, NAT = global/private address translation, auto-negotiation = automatic determination of communication speed/mode.
用語