100 Days of Cloud – Day 58: Azure Content Delivery Network

Its Day 58 of my 100 Days of Cloud journey, and todays post is a quick overview of Azure Content Delivery Network.

A content delivery network is a global distributed network of servers that deliver cached to users based on their location. Examples of content that can be delivered via a CDN is Websites or Blob Storage Data.

Overview

Azure CDN uses the concept of distributed servers called Point-of-Presence servers (or POPs for short). These POPs stored cached content on edge servers that are located close to the locations where the user requests the content from, therefore reducing latency.

The benefits of using Azure CDN to deliver web site assets include:

  • Better performance and improved user experience for end users.
  • Scaling for better hadling of high loads, such as product launches or seasonal sales.
  • Content is served to users directly from edge servers so that less traffic is sent to the origin server.

Azure CDN POP Locations are worldwide, and a full list can be found here.

How it works

Image and Steps Credit – Microsoft
  1. A user (Alice) requests a file (also called an asset) by using a URL with a special domain name, such as <endpoint name>.azureedge.net. This name can be an endpoint hostname or a custom domain. The DNS routes the request to the best performing POP location, which is usually the POP that is geographically closest to the user.
  2. If no edge servers in the POP have the file in their cache, the POP requests the file from the origin server. The origin server can be an Azure Web App, Azure Cloud Service, Azure Storage account, or any publicly accessible web server.
  3. The origin server returns the file to an edge server in the POP.
  4. An edge server in the POP caches the file and returns the file to the original requestor (Alice). The file remains cached on the edge server in the POP until the time-to-live (TTL) specified by its HTTP headers expires. If the origin server didn’t specify a TTL, the default TTL is seven days.
  5. Additional users can then request the same file by using the same URL that Alice used, and can also be directed to the same POP.
  6. If the TTL for the file hasn’t expired, the POP edge server returns the file directly from the cache. This process results in a faster, more responsive user experience.

In order to use CDN, you need to create a CDN Profile in your Azure Subscription. A CDN Profile is a collection of CDN Endpoints, and you can configure each endpoint to deliver specific content. You can then use the CDN profile in conjunction with your Azure App Service to deliver the App to the CDN locations in your Profile.

However one thing to note, if you are delivering different content types, you will need to create multiple CDN profiles. There are limits set per Azure Subscriptions on CDN, details can be found here.

There are different pricing tiers in CDN which apply to different content types, and you can avail of CDN Network services from Akamai or Verizon as well as Microsoft. You can find full details on pricing here.

Conclusion

You can get a full overview of Azure Content Delivery Network from Microsoft docs here. Hope ou enjoyed this post, until next time!

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