問81
頻出度★★★
無線LAN に関する記述のうち, 適切なものはどれか。
平成26年度 春期 ITパスポート試験 問81
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 81
Incorrectア
Wireless LAN is not limited to PCs. Smartphones, tablets, printers, TVs, game consoles, and various IoT devices can all use it as long as they have a wireless LAN function. The restriction “it cannot be used with anything other than a PC” is therefore wrong.
- イ
正解 The correct answer is イ. A wireless LAN has two operating modes: infrastructure mode, in which communication is relayed through an access point (the base unit), and ad hoc mode, in which terminals connect directly to each other by radio waves without going through an access point. In ad hoc mode, two PCs or two game consoles can communicate one-to-one (peer-to-peer), and no access point is needed. Wi-Fi Direct is a standardized mechanism based on the same idea, and it is used for things like printing directly from a smartphone to a printer. Therefore, “There is an operating mode that allows one-to-one communication even without an access point” is an appropriate statement.
Incorrectウ
Encryption standards have not been unified into a single one. Several standards exist, such as WEP, WPA, WPA2, and WPA3, and they have gone through generational changes as vulnerabilities were discovered. Older standards such as WEP, which are considered unsafe and are not recommended, still remain, so “unified into a single standard” is wrong.
Incorrectエ
Because wireless LAN uses radio waves, the signal attenuates as the distance grows even when there are no obstacles, so the range in which communication is possible is limited. For typical indoor use the guideline is around several tens of meters, so communication “regardless of distance” is not possible.
ここがポイント
- The two operating modes of wireless LAN: infrastructure mode, which goes through an access point, and ad hoc mode, in which terminals connect directly to each other (Wi-Fi Direct belongs to the same family) — one-to-one communication without an access point is possible.
- Basic properties of wireless LAN: devices other than PCs can use it as long as they support it; there are multiple generations of encryption standards such as WEP / WPA / WPA2 / WPA3; and since it uses radio waves, there is an upper limit on communication distance.
用語