Knowledge points involved
What is a domain name, the concept of a domain name, the structure of a domain name, the addressing process of a domain name address, and an in-depth understanding of the addressing mechanism of a domain name.
原创于：CSDN博主-《拄杖盲学轻声码》，更多内容可去其主页关注下哈，不胜感激
Article Directory
foreword
更多考试总结可关注CSDN博主-《拄杖盲学轻声码》
1. The concept of domain name
Through the previous study, we know that the way to identify a computer on the Internet is to use the IP address. But a set of IP address numbers is not easy to remember. Therefore, it is necessary to choose a meaningful and easy-to-remember name for the server on the Internet. This name is called a domain name (Domain Name).
For example, as far as the portal website of the Beijing Municipal Government is concerned, most users will enter www.beijing.gov.cn when browsing this website, and few people will remember the IP address of this server , www.beijing.gov.cn is the domain name of "Window of Beijing", and 210.73.64.10 is its IP address, just like when we call a friend, we must call him by his name, almost no one calls the other party's identity card number.
However, since the IP address is the real distinction between machines on the Internet, when a user enters a domain name, the browser must first go to a host computer with a database corresponding to the domain name and IP address to query the IP address of the computer. And this queried host is called Domain Name Server (Domain Name Server), referred to as DNS, for example: when entering www.beijing.gov.cn, the browser will send the name www.beijing.gov.cn to the nearest DNS server for analysis, if found, it will return the IP address of this host, but if not found, the system will prompt "DNS NOT FOUND (DNS server not found)", so once the DNS server does not work It's like the road sign is completely destroyed and no one knows where to send the material.
2. Domain name structure
The host name of a host is composed of the domain names of all levels of domains to which it belongs and the name assigned to the host. When writing, according to the order from small to large, the top-level domain name is placed on the far right, the name assigned to the host is placed on the left, and the names of all levels are separated by ".".
In the domain name system, common top-level domain names are divided into organizational models. For example, the domain name www.ibm.com, because its top-level domain name is com, it can be deduced that it is the website address of a company. In addition to the org-mode TLD, the other TLDs correspond to geographic patterns. For example, the domain name www.tsinghua.eu.cn, because its top-level domain name is cn, it can be deduced that it is the website address of China. Table 1-1 shows common top-level domain names and their meanings.
Table 1-1 Common top-level domain names
| TLD | TLD | TLD | TLD |
|---|---|---|---|
| com | business organization | cn | inside China |
| edu | educational institution | hk | China Hong Kong |
| gov | government department | mo | Macao, China |
| mil | military department | tw | Taiwan, China |
| net | Main Network Support Center | us | U.S. |
| int | International organizations | uk | U.K. |
| org | Organizations other than the above | jp | Japan |
The management rights of top-level domains are assigned to designated management agencies, and each management agency continues to divide the domains it manages, that is, divides them into second-level domains and grants the management rights of second-level domain names to their subordinate management agencies. A hierarchical domain name structure is formed, and the figure below shows the domain name structure of the Internet.
Domain names for the Internet are registered and managed by the Internet Society's committee responsible for network address allocation. There are currently three large network information centers in the world: INTER-NIC is responsible for the United States and other regions, RIPE-NIC is responsible for the European region, and APNIC is responsible for the Asia-Pacific region. China Internet Network Information Center (CNNIC, China Internet Network Information Center) is responsible for the management of my country's top-level domain name cn, and is responsible for providing IP address, autonomous system AS number and Chinese domain name allocation management services for my country's Internet service providers (ISP) and network users.
3. Addressing process of domain name address
The domain name address is widely used because it is easy to remember, and the IP address is also used when looking for the "called" in the Internet network, so the job of the domain name server is to specialize in the conversion and translation between the domain name and the IP address. The domain name address structure itself is hierarchical, so the domain name server is also hierarchical.
Give an example to illustrate the addressing process in the Internet. A foreign user wants to find a Chinese host named host.edu.cn, and the process is described as follows.
(1) The user "calls" host.edu.cn, and the local domain name server accepts and analyzes the number;
(2) Since the local domain name server does not have Chinese domain name data, it must inquire to the higher level, and the local domain name server asks the local highest domain name server (3 )
The highest local domain name server retrieves its own database, finds that cn is China, and points to the highest domain name server in China; (
4) Analyzes the number of the highest domain name server in China, and sees that the second-level domain name is edu, then points to edu Domain name server, as can be seen from the figure, ca domain name server and edu domain name server are at the same level;
(5) After analyzing the edu domain name server, find the IP address corresponding to the host in the domain, and point to the host named host, so , a complete addressing process ends.
Note: To really realize the connection on the line, it still has to go through the communication network. Therefore, the process of analyzing the domain name address by the domain name server
is actually the process of finding the IP address corresponding to the domain name address. It can be seen from this that the domain name server is actually a database, which stores the corresponding relationship between domain names and corresponding IP addresses of hosts and networks within a certain range.
Salary increase support area
I hope that everyone can learn more through this article, and the salary will increase year by year!
If you like bloggers, you can go to the list to find out. Bloggers specially set up a salary increase list for everyone to check. If you like it, you can click here to view it .
Summarize
更多资料大家可以关注csdn博主-《拄杖盲学轻声码》
The above is what I want to talk about today. This article mainly introduces what is a domain name and the practical application of domain name technology. I also look forward to sharing more with you. Let’s give it a thumbs up from handsome guys and beauties. Let’s work together in 2023! ! !