1. What is a CDN?
The full name of CDN is Content Delivery Network, that is, content distribution network. The basic idea is to avoid bottlenecks and links on the Internet that may affect the speed and stability of data transmission as much as possible, so as to make content transmission faster and more stable. By placing node servers all over the network to form a layer of intelligent virtual network based on the existing Internet, the CDN system can real-time according to the network traffic and the connection of each node, the load status, the distance to the user and the response time and other comprehensive information to redirect the user's request to the service node closest to the user. Its purpose is to enable users to obtain the required content nearby, solve the congestion situation of the Internet network, and improve the response speed of users' access to websites.
Simply put, content distribution network is a strategically deployed overall system, including four requirements of distributed storage, load balancing, network request redirection and content management, while content management and global network traffic management are the core of CDN where. By judging by user proximity and server load, CDN ensures that content is served to user requests in an extremely efficient manner.
2. What is DNS?
Domain Name System (English: Domain Name System, abbreviation: DNS) is a service of the Internet and a system for resolving the naming of online machines on the Internet . As a distributed database that maps domain names and IP addresses to each other, it can make people Access the Internet more easily. DNS uses UDP port 53. Currently, the limit for the length of domain names at each level is 63 characters, and the total length of domain names cannot exceed 253 characters.
Just like visiting a friend, you must first know how to get there. When a host wants to visit another host on the Internet, you must first know its address. The IP address in TCP/IP is a number separated by four segments separated by "." Composition (the IPv4 address is taken as an example here, and the IPv6 address is the same), it is not as convenient to remember as the name, so the domain name system is used to manage the correspondence between the name and the IP.
Although nodes on the Internet can be identified by IP addresses and can be accessed through IP addresses, even if the 32-bit binary IP address is written in the form of four tens digits from 0 to 255, it is still too long and difficult to remember. . Therefore, people invented the domain name (Domain Name), which can associate an IP address with a set of meaningful characters. When a user visits a website, he can either input the IP address of the website or its domain name, and the two are equivalent in terms of access. A company's Web site can be regarded as its online portal, and the domain name is equivalent to its address. Usually, the domain name uses the company's name or abbreviation.
Brief description in one sentence: DNS scheduling is one of the common scheduling methods of CDN.
3. What is ADN?
Application Delivery Network (ADN for short), which uses corresponding network optimization/acceleration equipment to ensure that users' business applications can be quickly, safely and reliably delivered to internal employees and external service groups. From the definition, we can see that the purpose of application delivery is to ensure the reliability, availability and security of key business of the enterprise . Application delivery should be the same goal of various technologies, such as WAN acceleration, load balancing, web application firewall... There are different product support and emphases for different application requirements.
ADC is an upgrade and extension of traditional network load balancing. It is a comprehensive delivery platform device that integrates load balancing, TCP optimization management, link management, SSL VPN, compression optimization, intelligent network address translation, advanced routing, and intelligent A comprehensive platform of various technical means such as port mirroring.
In one sentence: The difference between ADN and CDN is that one focuses on content distribution, and the other focuses on application delivery.
4. What is SCDN?
SCDN (Secure Content Delivery Network), which is a CDN service with security protection capabilities , provides stable acceleration while intelligently predicting attack behavior, and switches DDoS attack requests to high-defense IPs through an intelligent scheduling system to complete cleaning, while real user requests Then resources are normally obtained from the acceleration node. The distributed architecture of the acceleration nodes also has the ability to prevent CC attacks, achieving both acceleration and security.
The structure of SCDN is basically the same as that of the whole site. The difference is that the CDN node not only has the acceleration function, but also has a firewall . All requests are sent to the CDN node. The advantage of this is that the source server IP is hidden, so that attackers cannot Directly attack the source site. Second, because the CDN node is equipped with a firewall, it can resist most DDOS and CC attacks. Using highly resistant IPs to protect the source site cannot achieve both acceleration capabilities, but in areas such as online games, financial services, government and enterprise security, e-commerce, medical services, etc., which are not only vulnerable to attacks but also have acceleration capabilities, they must It is necessary to have both high defense capabilities and efficient secure CDN services.
In one sentence: The difference between SCDN and CDN lies in the increased security protection capability of CDN.
5. What is DCDN?
Site-wide acceleration DCDN (Dynamic Route for Content Delivery Network) is a cloud technology upgrade based on CDN acceleration technology, which distinguishes browsing of dynamic and static content wisely. Directly use CDN to accelerate static content; carry out efficient back-to-source pull for dynamic content, such as routing decision optimization, protocol optimization, etc. Site-wide acceleration DCDN can not only provide basic CDN static resource acceleration, but also further provide dynamic acceleration, TCP and UDP four-layer acceleration, Websocket seven-layer acceleration and other capabilities, which can quickly integrate security, edge computing and other capabilities into the whole site Accelerated global nodes improve site-wide performance and user experience, and improve business efficiency.
In one sentence: The difference between DCDN and CDN lies in the enhanced dynamic acceleration function.
6. What is ECDN?
ECDN (Enterprise Content Delivery Network) full-site acceleration is an all-round acceleration platform launched by Tencent Cloud in 2019. It is upgraded from the original DSA dynamic acceleration product. ECDN is suitable for one-stop acceleration of mixed dynamic and static resources. The same platform It can realize simultaneous acceleration of all types of resources in the station , and automatically identify dynamic and static resources. Static resources can be intelligently allocated to the optimal service node based on Tencent's self-developed GSLB system; dynamic resources can be quickly returned to the source based on the back-to-source routing optimization technology.
Brief description in one sentence: ECDN is still an ordinary CDN technology, and its basic logic is similar to that of DCDN, except that the way Tencent named it is different from other CDNs.
7. What is PCDN ?
The full name of PCDN in English is P2P CDN, and its Chinese name is P2P content distribution network. It is low-cost and high-quality content distribution network service constructed based on P2P technology by mining and utilizing massive fragmented idle resources on the edge network . You can access the service by integrating PCDN SDK (hereinafter referred to as SDK) to obtain the same (or slightly higher) distribution quality as CDN, while significantly reducing distribution costs.
Customers can obtain the same (or slightly higher) distribution quality as CDN after accessing the service through the integrated PCDN SDK (hereinafter referred to as SDK), while significantly reducing distribution costs. It is suitable for business scenarios such as video on demand, live broadcast, and large file download.
Brief description in one sentence: PCDN=P2P+CDN fusion.
8. What is Fusion CDN?
Converged CDN is based on traditional CDN, and integrates high-quality nodes of major CDN manufacturers through technical means to realize intelligent scheduling and accelerated management services with full business processing capabilities . Converged CDN breaks the dilemma of a single CDN manufacturer's limited node resources and scheduling capabilities, breaks through the limitations of geographical time and different operators, and uses a powerful intelligent scheduling strategy to comprehensively utilize the above resources to solve problems in actual scenarios, which can bring Better service effect, more stable quality and relatively lower service cost.
Brief description in one sentence: Converged CDN = access to several CDNs, adopt intelligent monitoring, which one has the best acceleration effect.
The above are the basic differences between CDN, DNS, ADN, SCDN, DCDN, ECDN, PCDN, and integrated CDN compiled by Huosanyun. Have you learned it yet?