This question's explanation and your answers so far.
PCやサーバ，通信機器，プリンタなどの間で通信を行う事例のうち，WANを使う必要があるものだけを全て挙げたものはどれか。 a サーバルーム内で，PCとWebサーバを同一のハブに接続し，PCからWebサーバに会社紹介のWebページをアップロードする。 b 大学の構内LANのアクセスポイントにノートPCを接続し，同じ構内にあるWebサーバから講義資料をダウンロードする。 c 東京本社内のLANに接続されているファイルサーバに大阪支社のPCからアクセスし，ファイルをダウンロードする。
This is “a, b”, but neither a nor b requires a WAN. In a, the communication is between devices connected to the same hub inside a server room, and it is completed within a single premises, so only a LAN is enough. In b as well, the communication is with a Web server located on the same campus of the university, and it is completed with just the campus LAN. Listing a and b as examples that require a WAN is the mistake.
This is “a, c”, but even though c requires a WAN, a does not. In a, the communication is between a PC and a Web server connected to the same hub inside the same server room, and it is completed with only a LAN. Including a, which does not require a WAN, is the mistake.
It lists only “b”, but b is communication involving an access point and a Web server located on the same campus of the university; it is completed with just the campus LAN, and no WAN is needed. The example that requires a WAN is c, not b.
正解 A WAN (Wide Area Network) is a network that connects sites that are geographically far apart, and it is generally used by way of a telecommunications carrier’s lines. In c, a PC at the Osaka branch office accesses a file server on the LAN of the Tokyo head office. Because this communication spans the two distant sites of Osaka and Tokyo, a WAN that connects the two sites is required. Therefore, the only example that requires the use of a WAN is c, and “エ”, which chose “c”, is the correct answer.