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Domain Name Overview

(1) Domain name structure

(2) Domain name structure type

Root domain: refers to the root server, which is used to manage the main directory of the Internet. There are only 13 of them in the world. One is the main root server, located in the United States. The other 12 are auxiliary root servers, of which 9 are located in the United States; 2 in Europe, located in the United Kingdom and Sweden; and 1 in Asia, located in Japan. All root servers are managed by ICANN, the Internet Domain Name and Number Assignment Organization authorized by the US government, which is responsible for the management of the global Internet domain name root server, domain name system and IP addresses.

Top-level domain: includes organization domain and country/region domain. The rightmost part of the domain name is the country/region domain. The country code consists of two letters, such as .cn, .uk, .de and .jp. .cn is the top-level domain for China. On the left side of the country/region domain is the organization domain. Common .com is used for commercial organizations, .net is used for network organizations, and .org is used for

Used by a variety of organizations including non-profits.

Second-level domain name: The domain name before the top-level domain name. In front of the top-level domain name, it refers to the online name of the domain name registrant, such as baidu, ibm, yahoo, microsoft, etc.

FQDN: is the host name.DNS suffix, which means the host name plus the full path, which lists all domain members in the sequence. The full domain name can accurately indicate where the host is logically located, or it can be said that the full domain name is a complete representation of the host name. The information contained in the full domain name can show the position of the host in the domain name tree.

2. Hosts file

1) The role of the Hosts file

To access a website on the Internet, the domain name to be accessed must first be resolved into an IP address through a DNS server before the computer can access the website on this network domain name.

(2) Modify the Hosts file

In Windows system, the Hosts file is stored in the directory c:\windows\system32\drivers\let\cl and can be modified with Notepad. In CentOS system, the Hosts file is stored in the directory /etc/ and can be modified with vim\etc/hosts, such as adding the following code to the file.

127.0.0.1      www.baidu.com

When you visit www.baidu.com and find a mapped IP address in the local hosts file, you will visit this IP address.

3.DNS

On the Internet, there is a one-to-one correspondence between domain names and IP addresses. Although domain names are easy for people to remember, machines can only recognize each other's IP addresses. The conversion between them is called domain name resolution, which must be completed by a special domain name resolution system. DNS is the system for domain name resolution.

Static mapping: Each device is configured with a mapping from host to IP address. Each device independently maintains its own mapping table, which is only used by the device.

Dynamic mapping: Establish a domain name resolution system (DNS), and only configure the mapping of host to IP address on a dedicated DNS server. Devices on the network that need to communicate using host names must first query the DNS server for the IP address corresponding to the host.

4. Domain Name Registration

(1) Prepare application materials: For com domain name, you do not need to provide ID card, business license and other information. For cn domain name, you are allowed to apply for individual registration, so you need to provide ID card or business license.

(2) Find a domain name registration website: Since different domain name suffixes such as .com and .cn are managed by different registration management agencies, if you want to register a domain name with a different suffix, you need to find a top-level domain name registration service agency authorized by the registration management agency.

(3) Query the domain name: After successfully registering a user name on the domain name registration query website, query the domain name, select the domain name to be registered, and click Register;

(4) Formal application: After finding the domain name you want to register and confirming that the domain name is available for application, submit the registration and pay the annual fee;

(5) Application success: After the formal application is successful, you can start to enter the DNS resolution management, set the resolution record and other operations.

Web pages and HTML

1. Website Overview

A web page is a file stored in a computer somewhere in the world, and this computer must be connected to the Internet. A web page is identified and accessed through a URL, and is a "page" on the Internet. A web page may include the following content:

Text: Text is the most important information carrier and communication tool on a web page. The main information on a web page is generally in text form.

Image: Image elements have the function of providing information and displaying intuitive images on web pages.

■ Static images: They may be pictures or vector graphics on the page. Picture formats are usually GIF, JPEG or PNG, etc.; vector formats are usually SVG or Flash.

■Animated images: Usually animations are GIF and SVG.

Flash animation: The role of animation in web pages is to effectively attract more attention of visitors.

Sound: Sound is an important component of multimedia and video web pages.

Video: The use of video files makes the web page more exciting and dynamic.

Table: A table is used to control the layout of page information on a web page.

Navigation bar: The navigation bar is a set of hyperlinks on a web page, and the destination of the connection is the important page on the web page.

Interactive form: Forms are usually used on web pages to connect to databases and accept data entered by users in the browser, using the database to provide more interaction between the client and the server.

Web page related concepts are as follows:

Domain name: It is the URL entered when browsing the web.

HTTP: A communication protocol used to transmit web pages. When using a browser to access a URL, you need to add http:/l in front of the domain name, indicating that the web page is transmitted using the http protocol.

URL: is a World Wide Web addressing system that represents the location path of a resource on the network.

HTML: is the Hypertext Markup Language for writing web pages.

Hyperlink: has the function of linking different web pages in a website.

Publishing: The process of uploading the prepared web pages to the server for users to access.

2. HTML Overview

HTML files can be edited using any text editor that can generate txt files. To generate a Hypertext Markup Language file, just change the file name suffix to ".html" or ".htm".

3. HTML Basic Tags

(1) HTML syntax rules

HTML tags use double tags, with the front and back tags corresponding to each other, indicating the start and end of the tag respectively. The content between the tags is described by the tags. The front tag is represented by "", and the end tag has an extra "", represented by "".

(2) HTML file structure

The outermost layer of an HTML document consists of

It indicates that the file is described in HTML language. It contains the header tag ( ) and content tag ( ) in parallel. The most basic HTML file structure is as follows:

4. Website and Home Page

A website is made up of web pages, containing multiple web pages, a collection of content with an independent domain name and independent storage space. These contents may be web pages, programs or other files.

Static and dynamic web pages

1. Static web pages

In website design, web pages in pure HTML format are usually called "static web pages". Static web pages are standard HTML files with file extensions such as .htm or .html.

2. Dynamic web pages

The so-called dynamic web pages refer to a web programming technology that is opposite to static web pages.

3. Dynamic web language

Early dynamic web pages mainly used Common Gateway Interface (CGI) technology. Although CGI technology has matured and has powerful functions, it is difficult to program, inefficient, and complex to modify, so it tends to be gradually replaced by new technologies.

HTTP Methods

HTTP Status Codes

HTTP request process analysis

1. Request message

2. Response message