What is CDN caching?
Content Delivery Network
, i.e. content delivery network, multiple sets of static storage services are deployed in various places. In essence, space is exchanged for time, and the nearest node content is automatically selected, and no further requests are made. The original server is suitable for storing static content that is rarely updated, and files are updated slowly.
Example:
You want to drink water. You have to go to the water room to get water every time. You find it troublesome, so you choose a kettle. Fill it with water, so you don’t have to go to the water room to pick up water every time. You can choose the nearest kettle to pick up water.
How to do?
Try to avoid bottlenecks and links on the Internet that may affect the speed and stability of data transmission, so that content transmission can be faster and more stable.
A layer of intelligent virtual network based on the existing Internet is formed by placing node servers throughout the network.
The CDN system can redirect the user's request to the service node closest to the user based on comprehensive information such as network traffic and the connection of each node, load status, distance to the user, and response time in real time.
CDN advantages:
Local Cache acceleration improves the access speed of enterprise sites (especially sites containing a large number of pictures and static pages), cross-operator Network acceleration ensures that users on different networks receive good access quality.
Remote access users intelligently automatically select Cache servers based on DNS load balancing technology.
Automatically generate the server's remote Mirror (mirror) cache server. When remote users access, read data from the cache server, reduce the bandwidth of remote access, share network traffic, reduce the load of the original site web server and other functions.
Widely distributed CDN nodes coupled with intelligent redundancy mechanisms between nodes can effectively prevent hacker intrusions.
Working principle:
##Traditional access: Users enter the domain name in the browser to send a request ->Resolve the domain name to obtain the server IP address ->Find the corresponding server based on the IP address->The server responds and returns data.
Use CDN to access: Users send requests->Intelligent DNS resolution (determine geographical location, access network type based on IP, select the server with the shortest route and the lightest load)-> ; Obtain the cache server IP -> Return the content to the user (if it is in the cache) -> Initiate a request to the origin site -> Return the result to the user -> Store the result in the cache server.
Applicable scenarios:
2. Large file download; 3. Live streaming website, etc.;
CDN implementation
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