Basic Concepts

This guide introduces basic concepts related to CDN, aimed at helping you understand and effectively use CDNetworks CDN products.

Origin Server

The origin server is your primary website server where your business operations are hosted and serves as the source for data acceleration and distribution. When a CDN edge server does not have the requested user content in its cache, it retrieves the content from the origin server and responds to the user. The origin server could either be CDNetworks object storage or your own origin server (It can be an IP address or a domain of your origin server).

CDN PoP

A CDN PoP(Point of Presence), also known as an edge server, caches content from customer origin servers to swiftly meet user access demands.

Acceleration Domain

An acceleration domain is the domain configured under CDN services, through which end-users access your services and enjoy fast-loading experiences provided by the CDN. For instance, after adding CDNetworks.com to a Content Acceleration or Dynamic Content Acceleration service, this domain becomes an acceleration domain. In our documentation, the acceleration domain may sometimes be referred to simply as “domain.”

CNAME Record / CNAME Domain

A CNAME record, or Canonical Name record, is a type of resource record in the Domain Name System (DNS) that maps an alias name to a true or canonical domain name. This is typically used in CDN services to associate a custom domain (the alias) with a CDN-provided domain (the canonical name), which ultimately resolves to the IP addresses of the CDN’s edge servers. Here’s how it works in the context of CDNetworks:

When you add an acceleration domain in the CDNetworks console, the system assigns a domain such as .wcdnga.com which serves as the CNAME domain. To implement this, you must configure a CNAME record with your DNS service provider. This CNAME record will direct requests for your custom domain (e.g., CDNetworks.com) to the .wcdnga.com domain. The DNS resolution process will then continue from the CDN’s domain to the actual CDN edge servers that cache and serve your content. This setup helps in distributing traffic across the global CDN infrastructure and accelerating content delivery by serving requests from the nearest edge server location.

Static Content

Static content includes content that return the same data in response to multiple requests, such as images, videos, web files (HTML, CSS, JS), and software packages. By caching static content from the origin server at CDN nodes globally, CDN enables users to access content needed nearby, thereby accelerating the access.

Dynamic Content

Dynamic content includes content that may return varied data in response to multiple requests, such as dynamic web pages (ASP, JSP, PHP, etc.), API interfaces, and database interaction requests.

Back to Origin

When a CDN edge server lacks the requested content in cache or the cache has expired, the server will go “back to origin” to retrieve the content from the origin server and respond to the user. This process is referred to as Back to Origin.

Origin Host

Also known as the Host header, this mandatory field in an HTTP request specifies the hostname or domain name of the server the client wishes to communicate with. It is essential because multiple domains can share the same origin IP address on an origin server, and the Host header identifies which domain the client is requesting.

Cache Prefetch

Cache prefetch is a proactive strategy that involves pre-loading large files or predicted popular content onto all CDN edge servers in advance. This allows users to immediately access cached files upon request, without waiting for data to be pulled from the origin, effectively reducing the origin server’s bandwidth pressure and enhancing file response speed.

Cache Purge

When the file versions on CDN edge servers become outdated, the cache purge feature allows for specifying file URLs or directories to delete outdated cached files within the edge servers. After purging, when a CDN edge server receives a user request, it retrieves the latest file from the origin server.