CDN (Content Delivery Network) is a key technology for optimizing network transmission. It achieves efficient content distribution and acceleration through distributed node deployment and intelligent scheduling mechanism. This article will systematically explain the technical definition, core functions, working principles and application scenarios of CDN, from node caching to traffic scheduling, and explain in detail how it solves problems such as network delay and bandwidth bottleneck. Whether it is page loading optimization of e-commerce platforms or smooth playback guarantee of video websites, CDN has become a standard technology for improving user experience. The following will conduct an in-depth analysis from the following dimensions.

　　1. Basic concepts of CDN

　　CDN (Content Delivery Network) is a content distribution network. By deploying massive edge nodes around the world, the source site content is cached to the node closest to the user, so that users can obtain resources without going directly to the source site. Its core advantage is to shorten the content transmission distance, reduce network latency, and solve the slow loading problem caused by cross-regional and cross-operator access. It is a key technology to improve the access speed of websites, APPs and other applications.

　　Screenshot 2025-04-14 113855

　　2. Working principle and technical architecture

　　The working mechanism of CDN can be broken down into four steps:

　　Request identification: When a user accesses, DNS resolution directs the request to the CDN node closest to the user;

　　Node cache: If the node has cached content, it will be returned directly to the user; if not, it will be obtained and cached from the source station;

　　Smart scheduling: Through load balancing technology, the optimal node is selected to respond to user requests;

　　Back-to-source update: After the source station content is updated, the CDN node will update the cache synchronously according to the strategy to ensure content consistency.

　　3. Distributed architecture composition

　　The CDN architecture includes three core components:

　　Edge node layer: Cache servers distributed around the world, directly responding to user requests, the number can reach thousands;

　　Regional center layer: Aggregate edge node traffic, responsible for regional distribution and scheduling of content;

　　Source station layer: Original content server, providing data update support for CDN nodes.

　　4. Core functions and technical advantages

　　CDN optimizes network experience in the following aspects:

　　Delay reduction: Through local access, cross-regional delay is reduced from 100ms + to less than 30ms, and the loading speed of mobile pages is increased by more than 50%;

　　Bandwidth saving: Static resources (pictures, videos) are carried by CDN nodes, and the bandwidth pressure of the source station is reduced by 60%-80%. After a certain video platform accesses CDN, the bandwidth cost is reduced by 4 million yuan/month;

　　Anti-concurrency capability: Edge nodes can independently handle traffic peaks, and the source station does not need to expand capacity due to sudden access. During the promotion period of a certain e-commerce company, CDN supported an average of 500 million visits per day.

　　5. High availability guarantee

　　The distributed architecture of CDN naturally has disaster recovery capabilities:

　　Node fault switching: When an edge node fails, the traffic is automatically dispatched to the adjacent node, and the service recovery time is less than 1 second;

　　Source station protection: Hide the source station IP address to avoid DDoS attacks directly targeting the source station. A game manufacturer reduced the source station attack traffic by 90% through the CDN + high defense combination.

　　6. Typical scenario application

　　CDN is indispensable in the following fields:

　　E-commerce platform: optimize the loading speed of product pictures and detail pages. After a head e-commerce company connected to CDN, the order conversion rate increased by 12%;

　　Video live broadcast: support millions of concurrent viewings, the freeze rate dropped from 15% to less than 3%, and a live broadcast platform achieved simultaneous live broadcast of cross-border events through CDN global nodes;

　　Mobile application: accelerate the download of pictures and resource packages in the APP. After a social APP connected to CDN, the loading speed of the new user installation package increased by 40%, and the retention rate on the next day increased by 8%.

　　Through distributed caching and intelligent scheduling, CDN fundamentally reconstructs the transmission mode of network content: converting centralized source station access into distributed edge acquisition not only solves the delay problem of cross-regional access, but also reduces the traffic cost of enterprises through bandwidth sharing. From the experience of opening e-commerce pages in seconds to the smooth playback of live broadcast platforms, CDN has become the "infrastructure" of digital services. Its value lies not only in acceleration, but also in providing users with a consistent high-quality experience.

　　In selection and application, enterprises need to select CDN services with wide node coverage and high cache efficiency according to the business coverage area, content type (static/dynamic) and traffic characteristics, and combine HTTPS, edge computing and other functions to achieve all-round optimization. With the popularization of 5G networks and the in-depth application of AI technology, CDN will further evolve into an "intelligent edge platform" in the future. It will not only undertake content distribution tasks, but also become a key node for edge computing and real-time data processing, providing more powerful technical support for the digital transformation of enterprises.