Big talk content delivery network (CDN)

Big talk content delivery network (CDN)

Content Delivery Network (CDN)The concept1995ByMassachusetts Institute of TechnologyProposed,YesAllows users to access the nearest network.Solution.The specific method is:Smart routing and traffic management technologies are used to direct users' access requests to healthy and fastest-responding CDN nodes in the CDN network. Users can directly access this CDN node, obtain the required content and data, and access to the nearest node accelerates the access speed.

By using the content delivery and replication mechanism, you do not need to change the original website structure. You only need to modify a small number of DNS configurations to accelerate the network response speed. When a user accesses a website using the CDN service, the resolution request is finally processed by the DNS domain name resolution server provided by the CDN service provider. It provides users with the node addresses that can respond quickly to users at that time, so that users can effectively and accurately get quick services. At the same time, it maintains real-time communication with all CDN nodes distributed in different locations, collects the health status of each node, and ensures the success rate of user access.

The above description is professional. Website access is actually a process of searching for website servers on users' computers. Let's take a look.Before using the CDN service, the user's Website access process is as follows:

1. the user enters the Domain Name of the website to be accessed in his browser. The browser first views a hosts file under the local system directory. The file is located in WINDOWS \ system32 \ drivers \ etc and has no extension, but can be opened in notepad. The line corresponds to the domain name and IP value. If the IP address corresponding to the domain name exists, the browser directly uses this IP address to access the website.
2. If the IP address corresponding to the domain name does not exist, the browser requests the resolution of the domain name to the local DNS server. The local DNS server is the DNS allocated by the local telecom or China Unicom.
3. The local DNS server goes to the root DNS server to find the authorized DNS record, and the record is returned to the local DNS server;
4. The local DNS server parses the host name according to the domain name resolution server request recorded on the website authorization. The domain name resolution server sends the IP address as the resolution result to the local DNS server.
5. The local DNS server returns the IP address to the user;

6. After obtaining the IP address, the user can access the website server. The website server provides the corresponding content and data to the user.

　　After using the CDN service, the user access process is as follows:

　　 First three stepsThe process is the same, from Step 4Start:
1. After a domain name resolution request is sent to the CDN resolution server, the server sends the node IP address with the fastest response speed of the domain name to the local DNS server, and the local DNS server sends the IP address to the user. Step 4 and Step 5.
2. After obtaining the IP address, the user sends an access request to the CDN node for the first access.
3. The CDN node sends the content data retrieved from the Origin Site Server to the user.

4. The CDN node caches a large amount of data. When other users access the same content, the content data is directly returned to the user to complete the entire process from request to service.

Currently, most CDN service providers are charged, and there are not many free CDN service providers. With the increase of such products, the competition between manufacturers will become increasingly fierce, service content, service items, and service quality will also be upgraded! Therefore, we believe there will be more and better free CDN services.