- A distributed network of servers that delivers web content closer to users.
- CDNs store cache content on edge servers to minimize end-user latency.
- 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 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.
- You are charged based on the number of rules.
- You are charged for outbound data transfers.
- The limit for the following resources is 25:
- CDN profiles
- CDN endpoints per profile
- Custom domains per endpoint