Shulou(Shulou.com)06/03 Report--

Compared with other CDN service providers, the main advantages of CDN include stable and fast, cost-effective, easy to use, efficient and intelligent. More users will ask about the advantage of stability and speed. Generally speaking, CDN is characterized by sharing the pressure on the origin server, avoiding network congestion, accelerating the distribution of website content in different regions and different scenarios, and improving the speed of resource access. The following is to introduce the composition of CDN.

CDN (Content Delivery Network or Content Distribution Network) is called "content distribution network" in Chinese.

Static resources & dynamic resources

Only static resources can be accelerated and accessed nearby by cache, while dynamic resources can only be generated by the origin server in real time, even if cached is meaningless.

However, if a dynamic resource specifies "Cache-Control" to allow caching for a short period of time, it becomes a "static resource" during that time and can be accelerated by the CDN cache.

Note: for static resources and dynamic resources, it is more accurate to say that as long as Cache-Control allows caching, it is static resources, otherwise it is dynamic resources.

CDN:

There are two key components: global load balancing and caching system, corresponding to DNS and cache proxy.

Global load balancing (Global Sever Load Balance)

Abbreviated as GSLB, it is the "brain" of CDN, and the most common way to implement it is "DNS load balancing" technology.

The main responsibility is to select a "best" node to provide services in the CDN private network when the user accesses the network, and to solve the problem of how to find the "nearest" edge node and "load balance" to the whole CDN network.

Cache system

Equivalent to the "heart" of CDN, using HTTP cache proxy technology. If the service capacity of the cache system is not enough to meet the needs of users, then the GSLB scheduling algorithm is useless no matter how good it is.

Hit & back to Origin

"hit" means that the resource accessed by the user happens to be in the cache system and can be returned directly to the user.

"Origin-pull" is on the contrary. It is not in the cache and must be taken back to the origin station by proxy.

If there is anything else you don't understand, you can find our CDN technical engineer on the official website. CDN technical engineer has more than ten years of experience in the industry, so it will be more detailed and professional than the editor's answer. Official website link www.yisu.com

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