This document describes what the Azure Content Delivery Network (CDN) is, how it works, and the features of each Azure CDN product. If you want to skip this information and go straight to a tutorial on how to create a CDN endpoint, see Using Azure CDN. If you want to see a list of current CDN node locations, see Azure CDN POP Locations.
The Azure Content Delivery Network (CDN) caches static web content at strategically placed locations to provide maximum throughput for delivering content to users. The CDN offers developers a global solution for delivering high-bandwidth content by caching the content at physical nodes across the world.
The benefits of using the CDN to cache web site assets include:
- Better performance and user experience for end users, especially when using applications where multiple round-trips are required to load content.
- Large scaling to better handle instantaneous high load, like at the start of a product launch event.
- By distributing user requests and serving content from edge servers, 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. Usually this is 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 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 Using Azure CDN.
To see the CDN in action, check out the video of our Build 2016 session.
For pricing information, see CDN Pricing.