問81
頻出度★★★
cookieによって得られる利便性の例として, 適切なものはどれか。
平成26年度 秋期 ITパスポート試験 問81
テクノロジ系ネットワーク › ネットワーク応用
This question's explanation and your answers so far.
解説
問 81
Incorrectア
“After registering in advance as a subscriber, only emails with content matching the registered category and preferences are automatically delivered” describes the subscription and delivery service of an email newsletter (mail magazine). The email address and desired categories that the user enters on the sign-up form are stored in a database on the server side, and messages are sent out from there by email; a cookie left with the browser is not involved at all. The delivery target is also email rather than a web page, which is another reason it is unrelated to the convenience provided by cookies.
Incorrectイ
“When you search using an Internet search engine, in addition to the search results, articles and advertisements with related content are also displayed” describes so-called keyword-linked search advertising (keyword matching), which lines up related articles and ads in response to the search keyword that was entered. What determines the displayed content is the keyword entered on the spot, not a cookie that retains a past browsing history. It does not identify a specific individual and works the same way for a user visiting the site for the first time, so it is a different mechanism from the per-user state retention provided by cookies.
Incorrectウ
“When you place a link to someone else's blog on your own blog, the other party is automatically notified of this” describes the trackback function of blogs. It is server-to-server cooperation realized by the linking blog system sending a notification request to the linked blog, and it differs from a cookie left with the visitor's browser in both mechanism and purpose. It does not perform the cookie's role of remembering an individual user's settings and restoring them on a return visit.
- エ
正解 The correct answer is エ. A cookie is a mechanism in which a web server temporarily leaves a small piece of data describing “what kind of user this is” with the browser, and the browser automatically sends that data back to the server when the user accesses the same site again. HTTP was originally a protocol in which each exchange completes its own connection and the server does not remember who accessed it last time (it is stateless), so on its own it cannot carry over the state of each individual user. Cookies are the representative means of “state retention (session management)” that compensates for this weakness, and they are used to keep a user logged in, to retain the contents of a shopping cart, and to remember per-user settings such as display language, character size, and region. Choice エ, “when a user accesses a website they have visited in the past again, the web page is displayed with settings tailored to that user,” is exactly the behavior in which the server reads the cookie left with the browser during the previous visit and builds the page for that user, so it is an appropriate example of the convenience provided by cookies.
ここがポイント
- Definition and role of a cookie: a mechanism in which a web server leaves a small piece of data with the browser and the browser sends it back on a repeat visit to the same site, so that the state of each individual user can be carried over even with stateless HTTP. Typical uses are keeping a login active, retaining a shopping cart, and remembering display settings and browsing history; the keywords are “revisit” and “per user.”
- Distinguish it from confusingly similar technologies: email newsletters (email delivery based on registered details), keyword-linked search advertising (display based on the keyword entered on the spot), and trackback (notification of an incoming link between blogs) all work without cookies. A good test is whether the choice contains wording that indicates state being carried over, such as “visited in the past” or “tailored to that user.” Also keep in mind that because cookies are tied to a user's activity history, they must be handled carefully from the standpoint of privacy protection.
用語