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

Content distribution network (Content Delivery Network, referred to as CDN) is a distributed network, which is established and covered on the bearer network, and is composed of server groups of edge nodes distributed in different areas. CDN shares the pressure on the origin server, avoids network congestion, ensures that the distribution of website content is accelerated in different regions and different scenarios, and improves the speed of resource access. Many users will encounter the problem of how to make effective use of CDN in the process of actual use of CDN. Today, I would like to interpret the concept, principle and function of CDN. So that we can have a better understanding in practical application.

What is CDN?

1. The full name of CDN is Content Delivery Network, that is, content distribution network.

2. CND acceleration mainly accelerates static resources, such as images and media uploaded on the website, as well as some Js, css and other files introduced.

3. CND acceleration depends on various network nodes. For example, 100 CDN servers are distributed nationwide. If you visit from Shanghai, you will return resources from the nearest node, which is the core.

4. The CND server stores resources by caching or actively grabbing the contents of the master server.

What kind of CDN is a good CDN?

1. Universal parsing + custom HTTPS/SSL+ hiding source IP is supported.

two。 Cache acceleration + permanent online + SEO optimization is supported. When the original server of the website goes down, if this feature is enabled, users can still access the website (what users see is cached data), thus achieving the effect of never interrupting the service of the website. it can help you solve the bad experience caused by server failure to visitors, and will not affect the inclusion of search engines. Thus does not affect the spider capture included SEO optimization ranking, can effectively solve the problem of instability of the origin server, and avoid being locked up by search engines.

3. Gzip compression is supported. Gzip is an encryption algorithm used in the http protocol. After the client sends a request to the web server, usually the server will return the page file and other resources to the client, and the client will render the file after loading. In this case, the file is generally large. If Gzip is enabled, the server will compress the page, JS,CSS and other text files or other files through a high compression algorithm. Then it is transferred to the client, and the browser of the client is responsible for decompressing and rendering. It usually saves more than 40% of traffic, and some PHP,JSP files can also be compressed.

4. Support intelligent scheduling + global acceleration. Here we will talk about the load balancing system: the main function is to schedule access to all users who initiate service requests and to determine the final actual access address provided to users. One is to determine the physical location of the cache that provides services to users through the "optimal" judgment of each service node according to the principle of proximity of users. The other is mainly responsible for the device load balancing within the node. In this case, it is necessary to have multiple telecom, mobile and Unicom nodes that can be accessed instantly in the world.

5. Support search engine origin-pull + hotlink protection. When the search engine crawler visits, it grabs the content on the source address directly instead of the cached content on each node (CDN). The hotlink protection function is based on the Referer mechanism supported by the HTTP protocol. It tracks the source through referer and identifies and judges the source. Users can identify and filter the identity of visitors by configuring the Referer blacklist and whitelist to restrict access to CDN resources.

If there is anything else you need to know, 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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