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What is CDN?

CDN (Content Delivery Network) refers to the content delivery network, also known as the content delivery network. This concept began in 1996 and was put forward by a research group of the Massachusetts Institute of Technology to improve the quality of service of the Internet. In order to publish rich broadband media content on the traditional IP network, they proposed to establish a content distribution platform based on the existing Internet to provide services for the website, and set up a special CDN service company in 1999 to provide professional services for Yahoo. Because CDN is a network coverage layer optimized to speed up network access, it is vividly called "network accelerator".

CDN allows rapid transfer of assets needed to load Internet content, including HTML pages, javascript files, stylesheets, images, and videos. The popularity of CDN services continues to grow. Properly configured CDN can also help protect websites from some common malicious attacks, such as distributed denial of service (DDOS) attacks. Today, most web traffic is served through CDN, including traffic from major sites such as Facebook, Netflix and Amazon.

The main functions of CDN are:

(1) Save the bandwidth of backbone network and reduce the demand for bandwidth.

(2) provide server-side acceleration to solve the problem of server overload caused by large user visits

(3) Service providers can use Web Cache technology to cache Web pages and objects visited by users locally, so that access to the same objects does not need to occupy the backbone exit bandwidth, and improve the corresponding time for users to visit Internet pages.

(4) it can overcome the problem of uneven distribution of websites, and reduce the cost of website construction and maintenance.

(5) reduce the influence of "communication storm" and improve the stability of network access.

Is CDN the same as the network host?

Although CDN does not host content and does not replace the need for proper web hosting, it does help cache content at the edge of the network, thereby improving site performance. By using caching to reduce managed bandwidth, help prevent service disruptions, and improve security, CDN is a popular choice to alleviate some of the major pain points caused by traditional web hosting. Many websites find it difficult to meet their performance requirements through traditional hosting services, which is why they choose CDN.

How does CDN work?

At the core of CDN is a network of connected servers that aims to deliver content as quickly, cheaply, reliably and securely as possible. To improve speed and connectivity, CDN places servers at switching points between different networks.

These Internet switching points (IXP) are the primary locations where different Internet providers connect to each other to provide access to traffic from their different networks. By connecting to these high-speed and highly interconnected locations, CDN providers can reduce the cost and time of high-speed data transmission.

What are the benefits of using CDN?

Although the benefits of using CDN depend on the size and requirements of the Internet attributes, for most users, the main advantages have the following four different components:

1. Reduce the loading time of a website

User patience declines rapidly as the site slows down, and because visitors are more likely to leave slow-loading sites, CDN can reduce bounce rates and increase the amount of time people spend on the site. In other words, the faster the site, the more sticky the user.

By using a nearby CDN server (and other optimizations) to distribute content near site visitors, visitors will be able to experience faster page load times.

CDN services can help reduce load time in the following ways:

1) the global distribution of CDN means reducing the distance between users and site resources. CDN allows users to connect to a geographically closer data center without having to connect to the site's origin server. Less transmission time means faster service.

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2) hardware and software optimizations, such as effective load balancing and solid state drives, can help data reach users faster.

3) CDN can use strategies such as extreme simplification and file compression to reduce file size, thereby reducing the amount of data transferred. Smaller files mean faster load time.

4) CDN can also speed up sites using TLS / SSL by optimizing connection reuse and enabling TLS fake start certificates.

two。 Reduce bandwidth cost

The bandwidth consumption cost of website hosting is the main cost of the website, and each time the origin server responds to a request, it consumes bandwidth. The processing and distribution of the original request by CDN can effectively reduce the bandwidth consumed by the origin server when responding to the request. Through caching and other optimizations, CDN can reduce the amount of data that must be provided by the origin server, thereby reducing hosting costs for site owners.

3. Increase content availability and redundancy

Heavy traffic or hardware failure may disrupt the normal function of the website. Because of the distributed nature of CDN, CDN can handle more traffic and withstand hardware failures better than many origin servers. One of the important features of CDN is its ability to keep website content online in the face of common network problems, including hardware failures and network congestion. By load balancing Internet traffic, using intelligent failover, and maintaining servers across multiple data centers, CDN is designed to avoid network congestion and withstand service disruptions.

Uptime is a vital part of anyone who owns Internet assets. Hardware failures and surging traffic caused by malicious attacks or increased epidemic may shut down the web server and prevent users from accessing the site or service.

The complete CDN has several features that minimize downtime:

1) load balancing. Load balancing distributes network traffic evenly among multiple servers, making it easier to expand the rapid growth of traffic.

2) Intelligent failover. Intelligent failover can provide uninterrupted service even if one or more CDN servers are offline due to a hardware failure, and failover can reassign traffic to other running servers.

3) if the entire data center encounters technical problems, Anycast routing diverts traffic to another available data center to ensure that no user loses access to the site.

4. Improve the security of the website

Information security is an indispensable part of CDN. CDN can improve security by providing DDoS protection, security certificate improvements, and other optimizations. At the same time, CDN can secure the site with new TLS / SSL certificates, which will ensure high standards of authentication, encryption, and integrity.

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