Introduction to DNS

Introduction to DNS

Thousands of hosts on the Internet are distinguished by IP addresses. When you know about IP addresses, it is hard to remember these numbers. Can we access each other in a form that is easy to remember? In this case, we have DNS (Domain Name ). It is because of the domain name system that we visit the mail website of Nanchang University and enter mail.ncu.edu.cn in the address column. CN: China Edu: cernet ncu: Nanchang University mail: email. Otherwise, you must remember the following IP address format every time you visit the Nanchang University email Website: 210.35.240.3. In contrast, is the preceding mail.ncu.edu.cn easier to remember?

But for a computer, it only knows 210.35.240.3, mail.ncu.edu.cn is meaningless to it. How can this conflict be solved? You can set up a server to find the corresponding IP address based on the domain name. Therefore, in the computer, DNS server settings are very important in TCP/IP attribute settings. Set the DNS server correctly. Otherwise, enter www.sina.com.cn. The computer does not know where to query the corresponding IP address. For computers, it makes no sense to know only the domain name. The DNS server settings are the same. There are two ways to do this: manual input, static, and network management. Another way is to dynamically obtain the IP address while also dynamically obtaining the DNS server.

The IP address of the DNS server of Nanchang University is 210.35.240.2, And the IP address of the backup DNS server is 202.101.224.68. That is to say, before accessing any website with a domain name, we need to first access this server, which resolves the domain name as an IP address and then perform subsequent operations.

You may ask, is the mail.ncu.edu.cn domain name set by ourselves or how can we decide? This is the same as the IP address. You cannot set it by yourself.

The following describes the domain name structure.

Top-level domain name

A domain name consists of two or more words separated by dots. The rightmost word is called a top-level domain name. Below are several common top-level domain names and their usage:

. Com -- used for commercial organizations. It is the most common top-level domain name. Anyone can register a domain name in. com format.

. Net-originally used for network organizations, such as Internet service providers and maintenance providers. Now anyone can register a domain name ending with. net.

. Org -- it is for various organizations, including non-profit organizations. Now, anyone can register a domain name ending with. org.

The Country Code consists of two letters for a top-level domain name such. CN ,. UK ,. de and. JP is called the country code top-level domain name (ccTLDs), where. CN is a top-level domain name dedicated to China and its registration is managed by CNNIC. second-level domain names ending with CN are referred to as domestic domain names. The rules and policies for the second-level domain names under the registered country code top-level domain names are related to the policies of different countries. When registering a domain name, you should consult the domain name registrar to obtain the relevant registration conditions and terms related to registration. In addition to registration services for domain names ending with. com,. net, and. org, some domain name registrars also provide registration for country-code top-level domain names. ICANN does not specifically authorize the Registrar to provide registration services for country code top-level domain names.

Second-level domain name

The next level of top-level domain name is what we call second-level domain name. Domainpeople.com: The domain name registrant provides a second-level domain name in the top-level domain name ending with. com. The domain name format may also be something.domainpeople.com. In this case, something is called the primary name or domain name.

 

Who is an international domain name management agency?

ICANN is a non-profit organization established in recent years to replace NSI. Its main functions include managing Internet domain names and address systems. Information about ICANN can be queried in the Web site http://www.icann.org.

Domain names at all levels on the Internet are managed by different organizations. Therefore, domain names managed by different organizations and domain name naming rules are also different. However, there are also some common naming rules for domain names, mainly including the following:

1. The domain name can only contain the following characters:

1. 26 English letters

2. "," 10 digits

3. "-" (in English)

2. combination rules of characters in a domain name:

1. The domain name is case-insensitive.

2. If the length of a domain name is limited, the naming rules for the domain name under CN are as follows: