A domain name (ドメイン名) is a text name, easy for people to read and remember, that points to a destination in place of an IP address, which is just a string of digits.
jp
co (companies, etc.)
ne (network services)
example.ne.jp
ac (universities, etc.)
Add your own name further to the left and you get the domain name example.ne.jp.
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Written with dots as in example.ne.jp, it has a layered structure in which each part further right is a broader division. The rightmost division is the top-level domain (トップレベルドメイン, TLD). Domain names appear in email addresses as well as web addresses: whatever follows the @ is the domain name.
AnalogyIt is like picking a friend's name in your contacts app to place a call, instead of memorizing their number.
How to rememberDomain means territory: inside the jp territory is ne, and inside ne is example, so the territory narrows as you read from the right.
Exam points
ExamA domain name (ドメイン名) is a text name for a destination, not the name of a communication protocol. It shows up in email addresses as well as web addresses.
ExamTo find the top-level domain (トップレベルドメイン) in a URL, look at the right end of the domain-name part, not the right end of the whole URL.
ExamRegistering a domain name is not limited to companies and organizations; individuals can do it too. Some domain names even contain kanji or hiragana.
DNS is a system that keeps track of which domain names go with which IP addresses and, when asked, uses one to look up the other.
Enter a name
Ask the DNS server
IP address returned
Connect to the web server
With that IP address as the destination, the PC connects to the web server.
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Converting between names and IP addresses is called name resolution (名前解決). When you enter a name in a browser, the PC first queries a DNS server (DNS サーバ), then connects using the IP address it gets back. The lookup also works the other way, from an IP address to a name.
AnalogyThink of a directory-assistance desk: give the person's name and it tells you their phone number.
How to rememberThe full name is Domain Name System; let the Name in the middle remind you of the clerk who looks up names.
Exam points
ExamDNS ties a name to an IP address (IP アドレス), not to a MAC address (MAC アドレス).
ExamAssigning IP addresses automatically is DHCP's job and accessing the web on a client's behalf is a proxy's (プロキシ); neither belongs to DNS.
ExamIf you cannot connect even with the correct name but can connect by entering the IP address directly, the prime suspect is a failed DNS server (DNS サーバ).
A URL is a way of writing where information on the internet, such as a web page, is located.
Part
Example
What it shows
Scheme
https
Communication method
Host name
www
A computer or the like within that domain
Domain name
example.ne.jp
Name of the destination
Path
/news/top.html
Where the information sits on the server
Short for Uniform Resource Locator, it looks like https://www.example.ne.jp/news/top.html. The scheme (スキーム) at the start gives the communication method, the domain name gives the destination, and the path (パス) at the end gives the location on the server. A host name (ホスト名) such as www to the left of the domain name refers to a computer or the like within that domain.
AnalogyLike a slip that reads "Central Library, floor 3, shelf B, fifth book."
How to rememberLocator means something that pins down a place. The L reminds you that a URL points to a location, not to the content.
Exam points
ExamA URL is a notation for where information is, not a communication protocol and not a grammar for writing page text.
ExamThe part immediately to the left of a domain name (ドメイン名) is the host name (ホスト名), which refers to a computer or the like within that domain. A file name appears on the path (パス) side.
A cookie is a small piece of data that a web server leaves with the visitor's browser, or the mechanism that does this.
First visit
Server issues data
Browser stores it
Sent back on return
When the user returns to the site, the browser sends the cookie and the server recognizes them.
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The next time the site is opened, the browser sends this data back, so the server can tell who is visiting. It is used for things like staying logged in and restoring display settings. Because the data sits in the browser on the PC used for viewing, it does not carry over to another PC.
AnalogyLike a dry cleaner's claim ticket: the customer keeps it, and showing it tells the shop whose items it is holding.
How to rememberPicture a cookie kept close at hand, and you will remember that the data sits on the user's side, not on the server.
Exam points
ExamCookies save effort while browsing, for example by showing a returning user a page with their settings.
ExamAn attack such as cross-site scripting (クロスサイトスクリプティング) can expose personal information held in a cookie. On a shared PC, clear cookies when you finish.
Mix-upA cache (キャッシュ) temporarily saves the viewed page itself as a file, whereas a cookie stores data handed over by the site.
RSS is a data format that describes a site's updates in a set form, with items such as titles, summaries, and dates.
Site updated
Feed published
RSS reader fetches it
New items listed
The user scans the list of new articles and opens the ones worth reading.
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The data each site publishes is called a feed (フィード) and is based on XML. Register the sites you want to follow in an RSS reader (RSS リーダ), and it gathers their feeds into a list of new articles. You learn about updates without opening each site in turn.
AnalogyLike a newspaper's list of headlines: instead of full text, you get headlines and short blurbs in a fixed layout, and you read only the stories that interest you in the paper itself.
How to rememberOne expansion is Really Simple Syndication. The S for syndication (distribution) reminds you it is a format for distributing content.
Exam points
ExamAn RSS reader (RSS リーダ) lists the titles and summaries of new articles from sources such as blogs (ブログ). It is not a tool for a blog's editing screen or for checking visitor counts.
ExamA feed icon (フィードアイコン) marks a site that offers a feed of its updates.
Mix-upCSS defines a page's design, while RSS describes update information. Only one letter apart, they do entirely different jobs.