問79
頻出度★★★
企業などの内部ネットワークとインターネットとの間にあって, セキュリティを確保するために内部ネットワークの PC に代わって, インターネット上の Web サーバにアクセスするものはどれか。
令和6年度 ITパスポート試験 問79
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 79
Incorrectア
A DNS server resolves names by mapping domain names (e.g., www.example.com) to IP addresses; it is not a relay that accesses Web servers on behalf of PCs.
Incorrectイ
An NTP server synchronizes the clocks of devices to an accurate reference time over the network; it has nothing to do with proxying Web access.
Incorrectウ
A streaming server delivers audio and video little by little (streaming); it does not have the role of accessing external Web servers on behalf of internal PCs.
- エ
正解 A proxy server (proxy) means “a substitute that acts on someone's behalf”; it is placed at the boundary between the PCs on the internal network and the internet, and serves as a relay that accesses Web servers on the internet on behalf of the PCs. A PC sends its request to the proxy server, and the proxy server makes the access on its behalf and returns the result. This keeps the internal PC's IP address from being exposed directly to the outside, and improves security and manageability through access-destination restriction (filtering), communication-log recording, content caching, and so on. It exactly matches the question's description of “accessing on behalf of the PCs on the internal network,” so the correct answer is “エ.”
ここがポイント
- Proxy server = a mechanism that, at the boundary between the internal network and the outside, relays communication as an agent for the PCs and ensures security through access restriction, log recording, and caching.
- Distinguish and remember the different roles of each kind of server: DNS (name resolution), NTP (time synchronization), streaming (audio/video delivery), and so on.
用語