Overview of the Azure Content Delivery Network
The Azure Content Delivery Network (CDN) caches static web content at strategically placed locations to provide maximum throughput for securely delivering content to users. The CDN offers developers a global solution for rapidly delivering high-bandwidth content by caching the content at physical nodes across the world.
This article describes the Azure CDN, how it works, and the features of each Azure CDN product. To skip this information and view a tutorial about how to create a CDN endpoint, see Getting started with Azure CDN. To see a list of current CDN node locations, see Azure CDN POP Locations.
The benefits of using a CDN to cache web site assets include:
- Better performance and improved user experience for end users, especially when using applications in which multiple round-trips are required to load content.
- Large scaling to better handle instantaneous high loads, such as the start of a product launch event.
- Distribution of user requests and serving of content directly from edge servers so that less traffic is sent to the origin.
How it works
- A user (Alice) requests a file (also called an asset) using a URL with a special domain name, such as
<endpointname>.azureedge.net. DNS routes the request to the best performing Point-of-Presence (POP) location, which is usually the POP that is geographically closest to the user.
- If the edge servers in the POP do not have the file in their cache, the edge server requests the file from the origin. The origin can be an Azure Web App, Azure Cloud Service, Azure Storage account, or any publicly accessible web server.
- The origin returns the file to the edge server, including optional HTTP headers describing the file's Time-to-Live (TTL).
- The edge server caches the file and returns the file to the original requestor (Alice). The file remains cached on the edge server until the TTL expires. If the origin didn't specify a TTL, the default TTL is seven days.
- Additional users may then request the same file using that same URL, and may also be directed to that same POP.
- If the TTL for the file hasn't expired, the edge server returns the file from the cache. This process results in a faster, more responsive user experience.
Azure CDN Features
There are three Azure CDN products: Azure CDN Standard from Akamai, Azure CDN Standard from Verizon, and Azure CDN Premium from Verizon. The following table lists the features available with each product.
* Verizon supports delivering large files and media directly via General Web Delivery.
Is there a feature you'd like to see in Azure CDN? Give us feedback!
To get started with CDN, see Getting started with Azure CDN.
To see the CDN in action, check out the video of the Build 2016 session.
For pricing information, see Content Delivery Network pricing.