問45
頻出度★★★
インターネットなどの共用のネットワークに接続された端末同士を, 暗号化や認証によってセキュリティを確保して, あたかも専用線で結んだように利用できる技術を何というか。
平成27年度 秋期 ITパスポート試験 問45
This question's explanation and your answers so far.
解説
問 45
Incorrectア
ADSL is a broadband access-line (connection means) technology that carries out high-speed data communication over existing telephone lines (analog lines). It provides the line itself and is not a technology that uses encryption and authentication to create a virtual dedicated line over a shared network, so it is incorrect.
Incorrectイ
ISDN is a communication service that digitizes telephone lines and handles voice and data in an integrated way. It, too, is a kind of line service, not a technology that builds a secure virtual dedicated line over a shared network through encryption and authentication, so it is incorrect.
- ウ
正解 A VPN (Virtual Private Network) creates a protected virtual tunnel over a shared network used by an unspecified large number of people, such as the Internet, through encryption and authentication, allowing communication to be carried out safely as if the parties were linked by their own dedicated line. Encryption prevents eavesdropping and authentication confirms that the other party is the correct one, so a level of confidentiality close to that of a dedicated line can be obtained while still using a public network. The option that matches all three elements of the stem, namely a shared network, security ensured by encryption and authentication, and being as if linked by a dedicated line, is choice ウ, VPN, which is the correct answer.
Incorrectエ
Wi-Fi is a wireless-LAN standard and technology that uses radio waves, a means of connecting terminals wirelessly over short distances. It is not a technology that lays an encrypted communication path equivalent to a dedicated line over the shared Internet, so it is incorrect (encryption of the Wi-Fi segment and a VPN that turns a public network into a virtual dedicated line serve different purposes).
ここがポイント
- VPN = a technology that lays a virtual tunnel protected by encryption and authentication over a shared network (such as the Internet), allowing safe communication as if over a dedicated line. Keywords: shared network, encryption and authentication, and as if a dedicated line.
- Distinguish that ADSL and ISDN are lines (access means) and Wi-Fi is a wireless LAN; none of them plays the same role as a VPN, which virtually turns a public network into a dedicated line.
用語