Azure Content Delivery Network

 

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

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
• Enable HTTPS to mitigate security threats on the content distribution network.
• 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

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.

Pricing

• You are charged based on the number of rules.
• You are charged for outbound data transfers.

Limits

• The limit for the following resources is 25:
  • CDN profiles
  • CDN endpoints per profile
  • Custom domains per endpoint