Content Delivery Network (CDN) is a popular service provided by many cloud providers, such as Alibaba Cloud. The main purpose of using CDN is to accelerate content delivery to users from across the globe. When using CDN, you are bound to encounter some technical jargon that may not be familiar to you. This article describes some of the most common terminology used in CDN.
Origin Server Source Station
The server used by the customer before the customer began implementing CDN. For example, if your website is hosted in the United States and you do not have any CDN, your Origin Server Source Station is the US.
User
Probably the most obvious one of all the terms, User refers to a visitor who accesses the website.
Last Mile
A common terminology used in network technology, last mile refers to the connection closest to the user. For CDN, this refers to the route between the visitor and CDN server they access.
Domain Name
A domain name is the name of a server or network system connected to the Internet. All domain names are unique worldwide. Domain names are closely related to Uniform Resource Locators (URLs). For example, in the URL https://www.alibabacloud.com/product/cdn, the domain name is www.alibabacloud.com.
CNAME Record
CNAME record stands for Canonical Name (CNAME) record. A CNAME record is an alias (alternate) to a domain name. For example, if we want to redirect users who access www.aliyun.com to the Alibaba Cloud homepage, we can use a CNAME record to point it to www.alibabacloud.com. A customer visiting the Aliyun domain name will see the same page as a different customer visiting the Alibaba Cloud domain.
CNAME Domain Name
CDN domain acceleration works by using CNAME records. After configuring the CDN acceleration on the Alibaba Cloud console, you will receive an accelerated domain name called the CNAME domain name (this domain name should be ".kunlun.com"). After the user directs their domain to the domain name ".kunlun.com" following the CNAME operation, the domain name resolution is formally transferred to Alibaba Cloud. All of the requests for this domain name will be transferred to the Alibaba Cloud CDN nodes.
DNS
DNS stands for Domain Name System. It refers to the domain name resolution service. On the Internet, DNS converts a domain name to an IP address that can be recognized by the network. People are more comfortable with readable domain names, but machines can only recognize IP addresses (numbers). There is a one-to-one correspondence between a domain name and an IP address, and the conversion between the two is called domain name resolution. Domain name resolution is automatically done by a dedicated domain name resolution server.
For example, the domain name www.baidu.com we enter will be automatically converted into the IP address 220.181.112.143
Edge Node
This is also called a CDN node or cache node. It is a simple concept proposed in contrast to the complex structure of the network. It refers to network nodes with a comparatively small number of links for the user to access. This improves the response capability and connection speed for the end user. Edge nodes are used to store the webpage content and objects with a higher traffic volume in a specialized cache machine on the server's front-end, to improve the speed and quality for website access.
Cache
Cache is a special memory subsystem in which frequently used data is temporarily stored to facilitate quick access. Cache in a memory stores content in frequently accessed RAM location as well as the storage address of the data. When the processor refers to an address in memory, the cache checks if it exists. If the address exists, the data is returned to the processor; and if the address is not stored, the memory is routinely accessed. Since cache is always faster than main RAM, cache is often used when RAM accesses will be slower than microprocessors.
