Azure Content Delivery Network Cheat Sheet

• A distributed network of servers that delivers web content closer to users.
• CDNs store cache content on edge servers to minimize end-user latency.

Critical Announcements

• Service Retirement Path: The CDN Standard from Microsoft (classic) product is on a retirement path. It will be retired on September 30, 2027, with restrictions on new profiles and managed certificates starting August 15, 2025. Azure CDN from Edgio was retired on January 15, 2025.

Features

• Improves the performance of dynamic web pages using dynamic site acceleration.
• You can set two types of caching rules in Azure CDN:
  • Global caching rule – overrides any HTTP cache-directive headers.
  • Custom caching rule – you can set a rule to match specific paths and file extensions.
• Types of origin:
  • Storage
  • Storage Static website
  • Cloud service
  • Web App
  • Custom Origin
• Protect content with custom domain HTTPS, DDoS mitigation, and Web Application Firewall (WAF) protection.
• Export basic usage metrics from your CDN by using diagnostic logs.
• With geo-filtering, you can set rules for different paths to allow or block content in selected countries/regions.
• CDN endpoint: <tutorialsdojo>.azureedge.net
• Modern CDN Replacement: Azure Front Door is positioned as the modern CDN replacement, offering high performance, scalability, secure user experiences, and Layer 7 load-balancing capabilities for applications.
• Dynamic Content Acceleration: Accelerates dynamic, non-cacheable content through network optimizations like route optimization to bypass Border Gateway Protocol (BGP).

How Caching Works

• Access the data quickly by storing the data in an origin server.
• If the file on the origin server has been updated, the cache must update its resource version.
• Azure CDN HTTP cache-directive headers:
  • Cache-Control – caching behavior of a browser.
  • Expires – a date based expiration time.
• Azure CDN HTTP cache validators:
  • ETag – a string that is unique to every file.
  • Last-Modified – the origin server compares the date with the last-modified resource header. 
    • Status code 200 = Modified
    • Status code 304 = Not Modified
• Default caching behavior:
  • Honor origin – honor the HTTP response cache-directive headers, if they exist.
  • CDN cache duration – how long a resource is cached on the Azure CDN.

Azure Content Delivery Network Pricing

• You are charged based on the product tier and usage, including outbound data transfers from Azure CDN POPs to the internet.
• You are charged for outbound data transfers.

Azure Content Delivery Network Default Subscription Limits

• Each Azure subscription has default limits for the number of CDN profiles, endpoints per profile, and custom domains per endpoint.
• The limit for the following resources is 25:
  • CDN profiles
  • CDN endpoints per profile
  • Custom domains per endpoint

Azure CDN Cheat Sheet Resources:

https://azure.microsoft.com/en-in/services/cdn/
https://docs.microsoft.com/en-us/azure/cdn/cdn-overview