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This article will explain in detail what the role of dns is, the editor thinks it is very practical, so share it with you for reference. I hope you can get something after reading this article.

The role of dns: to resolve domain names (URLs) to IP addresses, a process called DNS domain name resolution. The client sends a domain name query request to the DNS server; then the DNS server tells the client the IP address of the Web server; finally the client communicates with the Web server.

Introduction to DNS

DNS is a domain name resolution protocol

DNS is the abbreviation of Domain name system (Domain Name System) and a core service of the Internet. as a distributed database that can map domain names and IP addresses to each other, it makes it more convenient for people to access the Internet without having to remember the IP strings that can be read directly by the machine. This is also the official statement of DNS.

To put it bluntly: communicate through IP addresses on the Internet. However, the representation of IP addresses is numeric, which is difficult to remember (e.g. 116.213.120.232), so take a domain name form that is easier for humans to remember (such as www.google.com) for each IP, and use DNS to convert the resolved domain name into IP (parsing the convenient naming format into a format that the computer can understand, or translating IP into domain names).

The role of the DNS service: resolving domain names to IP addresses

The client sends a domain name query request to the DNS server (the DNS server has its own IP address)

The DNS server tells the client the IP address of the Web server

Client communicates with Web server

DNS query process (this is an important process to understand the principles of DNS)

Through hierarchical management, we can effectively manage hundreds of millions of domain name information around the world (similar to in a company, CEO only manages the managers of each department; the managers of each department only manage the team leaders of their own departments; each team leader only manages the team members of their own group. At least this is a more effective way of management.

The following is a process in which a client wants to access www.benet.com, a WEB server, to understand how DNS works

1. The client (PC) initiates a request to the preferred DNS server (the preferred DNS server refers to the DNS server to which your PC is currently connected, and Windows can be viewed using the ipconfig command): "do you know the IP of www.benet.com?" If the preferred DNS server knows (generally speaking, if the preferred DNS server has been parsed, it will be cached for a period of time. The default is three days. If it happens within the caching time, then the preferred server will know the IP of the domain name), then the preferred DNS server will directly return the IP address of the domain name to the client.

2. If there is no relevant information on the preferred DNS server, you cannot directly return the IP address of the domain name. In this case, the preferred DNS server will ask the root DNS server (all DNS servers know where the 13 DNS root servers are in the world). The root server may not know the IP address of this specific www.benet.com. But it knows the IP of the first-level domain com (that is, the root server is only responsible for maintaining all the first-level domains, so there are only a few hundred pieces of data here. Although the amount of data is small, it accepts requests from all over the world, so the load is heavy).

3. The root server returns the IP address of com to the preferred DNS server

4. The preferred DNS server is to request "com" DNS server: "do you know the IP of www.benet.com?", but the com DNS server does not know the IP of www.benet.com, but the com DNS server knows the IP of benet.com.

5. "com" DNS server returns this information to the preferred DNS server

6. The preferred DNS server is to request the "benet.com" DNS server, and then the benet.com server will of course know the IP address of www.benet.com.

7. "benet.com" DNS server returns this information to the preferred DNS server

8. The preferred DNS server returns the IP of the acquired www.benet.com to the client

9. The client accesses the WEB server according to the IP address of the www.benet.com obtained

10.WEB server returns relevant data

Domain name spatial structure

Expansion:

Why do you have to set up DNS to surf the Internet? Some friends may find out why I may log in to QQ and MSN, but I can't open the web page. In fact, most of the reasons are caused by the failure of the DNS server. The DNS server address is unique and is provided by the operator to the end user to analyze the relationship between the IP address and the domain name. If the DNS server address is not set, then it is impossible to query the destination of the address, and naturally the web page cannot be opened, while real-time chat software such as QQ and MSN uses the UDP transport protocol, that is, the unreliable transport protocol. You can also log in without providing a DNS server address.

This is the end of this article on "what are the functions of dns". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, please share it for more people to see.

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