With the rapid development of the Internet, people have higher and higher requirements for web page loading speed. In order to improve user experience, CDN (Content Delivery Network) came into being and became a key technology to make the website load faster. This article will introduce CDN and its working principle from an easy-to-understand perspective.
What is a CDN?
CDN, the full name of Content Delivery Network, is a kind of server deployed around the world that copies and stores static resources of the website such as pictures, style sheets, scripts, etc. to these servers to improve user access to the website. loading speed technology.
Simply put, CDN is like a courier on the Internet, distributing website content to all corners of the world, allowing users to obtain the information they need more quickly no matter where they are.
How CDN works
1. Static resource caching
The first step in how CDN works is to cache the static resources of the website on distributed servers. Static resources include images, style sheets, scripts and other files that do not change frequently, as opposed to dynamically generated content. These static resources will be copied to the CDN server and served from the server closest to the user when the user requests it.
2. Domain name resolution
When a user enters a URL into the browser and presses the Enter key, the browser will find the corresponding IP address through the Domain Name Resolution System (DNS). CDN uses this process to point the user's domain name resolution to the CDN node closest to the user, rather than directly resolving it to the website's original server.
3. Load balancing
CDN servers are distributed around the world, and users are also distributed in different geographical locations. Load balancing is one of the key features of CDN. It ensures that user requests are distributed to servers with lighter loads that are closest to the user, thereby improving response speed.
4. Content distribution
Once the user's request reaches the CDN node, the CDN determines whether the requested content is cached on its server. If there is, the cached content will be returned directly to the user; if not, the CDN will obtain and cache it from the website's original server, and at the same time spread the content to other CDN nodes to respond to the same request faster in the future.
5. Dynamic content processing
In addition to static resources, CDN can also handle some dynamically generated content. When a user requests dynamic content, the CDN will send the request to the website's origin server, obtain the latest content and return it to the user. Although there will be some delays in this process, because the CDN node is closer to the user, the overall loading speed will still be faster than directly requesting the original server.
Advantages of CDN
1. Speed up website loading speed
CDN distributes the content of the website to all parts of the world, allowing users to obtain the content they need from the server closest to them, greatly shortening the distance of data transmission, thereby improving the loading speed of the website.
2. Improve website stability and reliability
Due to the load balancing and content caching features of CDN, even if a certain server fails, users can still obtain the required content from other available servers, which improves the stability and reliability of the website.
3. Save bandwidth costs
CDN is distributed around the world, which can reduce the load on the original server and reduce bandwidth costs. In addition, because CDN can cache static resources, it reduces the number of requests to the original server and further saves bandwidth.
4. Improve global user experience
The distributed nature of CDN enables users to enjoy a faster and more reliable access experience around the world, and they can obtain website content faster no matter where they are.
Summarize
The emergence of CDN technology provides a powerful tool for improving user experience and website performance. Through a series of technical means such as static resource caching, domain name resolution, load balancing, content distribution and dynamic content processing, CDN effectively accelerates the network transmission process, allowing users to access websites faster and more stably. For website operators, using CDN technology can not only improve user satisfaction, but also reduce bandwidth costs. It is a technology worth considering and investing in.