DNS is the abbreviation of domain name system, which is used to name computers and network services organized into a domain hierarchy. DNS naming is used in TCP/IP networks (such as the Internet) to find computers and services through user-friendly names. When a user enters a DNS name in an application, the DNS service can resolve the name into other information related to it, such as IP address. Because, you enter the website, find the corresponding IP address through the domain name analysis system, and you can surf the Internet. In fact, the ultimate point of domain name is IP.
In IPV4, IP consists of 32-bit binary numbers. Divide these 32-bit binary numbers into four groups, each group has eight binary numbers, and convert these eight binary numbers into decimal numbers, which is the IP address we see, and its range is between 1 ~ 255. Because the maximum range of 8 binary numbers converted into decimal numbers is 1 ~ 255. Now it has started trial operation and will replace IPV6 in the future. The IP address will be represented by 128 binary digits.
As we all know, when we surf the Internet, we usually go to a website, such as www.sina.com.cn, which is actually a domain name. Computers on our computer network can only identify each other by IP address. For another example, when we go to the WEB server to request a web page, we can enter the web address or the corresponding IP address in the browser. For example, if we want to go to Sina, we can enter: www.sina.com.cn can also enter the IP address of 218.30.66.101,but we can't remember it or it's hard to remember it.
DNS: Domain name system Domain names are composed of a series of words or abbreviations separated by dots, and each domain name corresponds to a unique IP address. This naming method or a system that manages domain names in this way is called domain name management system.
DNS: Domain Name Server Although domain names are easy to remember, computers in the network can only know each other's IP addresses, and the conversion between them is called domain name resolution (for example, the conversion between www.sina.com.cn and 218.30.66.1kloc-0/above). Domain name resolution needs to be completed by a special domain name resolution server, and DNS is the server for domain name resolution.
1. What is DNS?
DNS refers to: domain name server. There is a one-to-one correspondence between domain names and IP addresses on the Internet. Although domain names are easy to remember, machines can only know each other's IP addresses. The conversion between them is called domain name resolution, which needs to be completed by a special domain name resolution server, and DNS is the server of domain name resolution.
2. Why register DNS? What's the point?
After applying for DNS, customers can resolve their own domain names or add subdomains. When applying for DNS, customers are advised to apply for two at a time.
3. What are the steps and regulations for registering DNS in the domain name registration agency?
At present, international domain's DNS must be registered in international domain, and domestic domain names' DNS must be registered in CNNIC.
(1) steps: log in to the member area-domain name service-domain name management-select a domain name as dns suffix-create a DNS server-choose to register internationally or domestically-apply-pay the fee.
(2) Cost: 75 yuan/Taiwan (one-time)
(3) Conditions: To register an international dns server, the name of the dns server must be an international English domain name registered in our company and have an independent IP address. The prefix before the domain name of DNS server is preferably DNS. ，ns。 Wait.
4. How long does it take for 4.DNS to register successfully?
Submit DNS registration application in the system, and the registration time is about 2 working days after receiving the payment.
5. How to modify the DNS server?
(1) Condition: The DNS to be changed is a legal DNS.
If you want to inquire whether the DNS is legal, please click: DNS inquiry interface.
Enter the name or IP address of the DNS server, select the third option, Nameserver, and inquire whether there is DNS registration information, such as the registrar and IP address corresponding to the name, then the DNS is legal.
(2) Modification method: change DNS through international domain registered by our company: users can log in to Wang Wan Member Area-paid product management-DNS modification to modify. If you want to modify the IP of a DNS server registered in Wang Wan, you can fax it to Wang Wan, indicating the name of the DNS server, the corresponding original IP address and the IP address to be modified, and affix the official seal of the company (individuals attach a copy of their ID cards). We will help the user to handle the business after confirming the business submitted by the user. The effective time is about 2 working days.
6. Is there a DNS charge for domain name modification?
Both international English domain names and domestic English domain names can modify DNS, and this service is free.
7. Why is DNS registered successfully, but it still cannot be used?
To register a DNS server, domain name resolution must be set for the host name of the DNS server to be registered on the DNS server of this domain name at the same time. Only after the resolution takes effect and the registration is successful can the newly registered DNS server be officially used.
For example, you want to register the domain names DNS1.abc.com (IP:1.1.) and dns2.abc.com(IP:
2.2.2.2), you must set dns1.abc.com to1.1.1.1in the existing DNS server in abc.com as soon as possible, and from dns2.abc.com to 2.2.2.2. In addition, if abc.com changes the DNS server in the future, it is necessary to set the above two records on the new DNS server to continue to use DNS.
8.DNS uses port 53.
Ports are roughly divided into three categories:
1: Known ports: From 0- 1023, they are bound to some services. Usually, the communication of these ports clearly indicates the protocol of a certain service. For example, FTP service opens port 2 1.
2. Registerd port: from1024-49151,it is loosely bound to some services, which means that many services are bound to these ports, and these ports also have many other uses. For example, many systems handle dynamic ports from 1024.
3. Dynamic and/or private ports: From 495 12-65535, these ports should not be allocated to services in theory. In fact, computers usually assign dynamic ports from 1024. Of course there are exceptions. SUN's RPC port starts at 32768.