On the day of Goddess Day, my girlfriend asked me what was the address of Taobao International. She wanted to see what was on taobao, so I sent her the website: https://world.taobao.com. This led to the following conversation.
First of all, what is a domain name, and then to introduce the various components of a domain name.
The domain name
Domain Name (Domain Name for short) is the Name of a computer or computer group on the Internet consisting of a series of characters separated by dots. It is used to identify the electronic location of the computer during data transmission.
IP address is the digital body identification of Internet host as a routing address, but it is not easy to remember, so the character identification of domain name, which is easier to remember than IP address. This is also an important function of domain names – to provide memorable names for digitized Internet resources.
For example, wikipedia.org is a domain name that corresponds to the IP address 208.80.152.2. People can access Wikipedia.org directly in place of an IP address, and the Domain Name System (DNS) will convert it into an IP address that is easy for machines to recognize. In this way, people only need to remember a string of characters called wikipedia.org with a particular meaning, rather than a number with no meaning.
In addition, domain names are unique. When resources change IP addresses, only the mapping between updated IP addresses and constant domain names is needed, which is insensitive to users. You can also access the new IP address using the original domain name.
Such as our common http://www.baidu.com, this is a standard domain name, no matter how Baidu company provides website services in the machine changes, this domain name is unchanged.
Let’s start from the front and introduce what the WWW is.
WWW, in fact, is the abbreviation of World Wide Web, Chinese translation for the World Wide Web. Is a system of interconnected hypertext accessible over the Internet. The World Wide Web is at the heart of the development of the information age and the main tool through which billions of people interact on the Internet.
World Wide Web and Internet
We usually call the Internet, the English name is called Internet. The Internet is a huge network of networks linked together at the beginning of the 21st century.
It is made up of millions of private, academic, corporate and governmental networks, from local to global, linked by a wide range of technologies, including electronic, wireless and fiber-optic networks.
This method of connecting computer networks to each other is called “network interconnection”. On this basis, a global network covering the whole world has been developed, which is called the Internet.
The Internet is not equivalent to the World Wide Web (WWW). The World Wide Web is just a global system based on hypertext links, and it is one of the services that the Internet can provide. The Internet has a wide range of information resources and services, in addition to file transfer (FTP), E-mail (E-mail), remote login (Telnet) and so on.
In order to distinguish the various applications in the Internet, there are different subdomains. For example, WWW is used as the subdomain name for the Internet, FTP is used as the subdomain name for file transmission, and Mail is used as the subdomain name for E-mail.
Therefore, we often see web sites may have www.mhcoding.cn, ftp.hcoding.cn, mail.mhcoding.cn, and so on in the form of subdomain names.
Omit the WWW
The World Wide Web is not exactly the same as the Internet, but it is the most important application of the Internet.
People who have had website construction may have such experience, when we buy a domain name, to do the resolution of this domain name, when the resolution needs to fill in the following information:
In the host record part, you can fill in the following contents:
In other words, domain names can be configured to be resolved. When we set WWW as the prefix of the domain name, we can visit the website by visiting www.aliyun.com. When we set @ as the domain prefix, go directly to Aliyun.com to access the site.
Because the World Wide Web is the most important part of the Internet, and the primary purpose of many domain names is to build Web sites, many companies will simply ignore the WWW.
The same domain name can be set to many resolutions. each resolutioncan be mapped to different IP addresses. For example, if we have a domain name mhcoding.cn, we can set www.mhcoding.cn resolutionto IP1, helloworld.mhcoding.cn resolutionto IP2 and so on.
The world.taobao.com mentioned in the article is resolved to an independent IP address by adopting the method of secondary domain name and using the prefix world.
Top-level domain names
A domain name consists of multiple levels. Looking backwards, the first level of a domain name is the top-level domain, which includes the generic top-level domain as well as the country and region top-level domains.
Generic Top-level Domains (gTLD) are one of the top-level domains (TLD) managed by the Internet Corporation for Assigned Names and Numbers (IANA). The agency is responsible for the Internet’s domain name system.
Such as:
Edu - for educational institutions. Gov - for government and its affiliates. Mil - for military institutions. Net - for Web service providers. Org - for organizations that do not fall into other generic top-level domain categoriesCopy the codeCountry code top-level domains (ccTLD) are two-letter abbreviations of countries or regions. Political considerations override technical and commercial considerations in the designation and allocation of domain names. These top-level fields are made up of two letters and most use the ISO 3166-1 standard.
For example, CN (mainland China), DE (Germany), EU (Eu), JP (Japan), HK (Hong Kong), TW (Taiwan), UK (UK), us (US).
So, not all websites end in.com, the average business website will end in.com, and the average educational website will end in.edu.
In China, domain names ending in.cn are also more common, because.cn is the top-level domain name representing the Chinese mainland.
In addition, there are also many Chinese top-level domains that can be used at present, such as. Chinese. I love you. China. Website. Shop. Company. Network. Group, restaurant, trademark, mall, etc.
