not all accesses are cached, and a large number of accesses are actually the first time, and not many people visit the same resource repeatedly.
moreover, the local browser cache can only hit the resources on the site that are used to build UI, and the hit rate for content that updates quickly is still very low. (for example, Weibo pictures, basically you refresh a few seconds is another pile of pictures).
CDN actually uses DNS, to resolve to different IP addresses (CDN servers) for users from different sources. The access is usually faster, while the content is cached in the server.
of course, without caching, CDN simply acts as a middleman (this is called reverse proxy ), because it is faster for users to access CDN than to access the original server. (for example, dynamic content is not cached)
and CDN can also break down the access pressure (there are load balancers within large websites, which is almost the same as reverse proxy, except that requests from the same entry are distributed to different servers for processing), and even resist DDoS attacks.
so there are still many benefits of CDN. Some large websites do not use CDN services, but put servers in multiple computer rooms, which is essentially the same reason.
CDN can decompose the pressure of static resource reading on the server and speed up the access speed of users. Because CDN uses DNS to resolve to different storage servers closest to the user. The speed of user access will be accelerated, and because each node server also stores our resource files, the server that accesses cdn greatly reduces the pressure on our own servers. In addition, basically, most websites have a lot of static resources, compared with less dynamic ones, so it is cost-effective to use CDN. After all, the loading speed is fast, and the user experience is good
CDN Content Delivery Network content distribution network. Using some DNS algorithms, you can access the corresponding node server resources nearby, which can speed up the access speed and reduce the load pressure on the main service cluster. It is often used in high concurrency scenarios. For example, if the main server of a business is in Shenzhen, and you are in Langfang, there is a corresponding node server in Langfang, and CDN will send Langfang's machine IP to your client, so you don't have to parse to the server in Shenzhen.
the full name of: Content Delivery Network or Content Ddistribute Network, is content delivery network
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CDN
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Internet
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Google
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ISPCDNIDCCDN
CDN
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CDN
and CDN is a smart courier. TA is not running around with brute force, bumping into
TA has also built a lot of delivery points, the nearest express (cache)
TA is good at optimizing the delivery path (scheduling) and will also repackage the package more reasonably (protocol optimization)
no matter where the user is in the world, as long as he is connected to the network. CDN service is like moving the origin server in front of users, the whole world is within reach!
CDN is to play the role of escort and accelerator, faster, more accurate and ruthless trigger information and reach every user, bringing a more extreme user experience.
