A content delivery network (CDN) is a globally distributed network of proxy servers, serving content from locations closer to the user.
Generally, static files such as HTML/CSS/JSS, photos, and videos are served from CDN, although some CDNs such as Amazon’s CloudFront support dynamic content.
Examples?? Akamai?
Push CDNs
Push CDNs receive new content whenever changes occur on your server.
You take full responsibility for:
providing content
uploading directly to the CDN
rewriting URLs to point to the CDN.
You can configure when content expires and when it is updated.
Uses:
Sites with a small amount of traffic or sites with content that isn’t often updated work well with push CDNs.
Content is placed on the CDNs once, instead of being re-pulled at regular intervals.
Pull CDNs
Pull CDNs grab new content from your server when the first user requests the content.
You leave the content on your server and take responsibility for:
rewriting URLs to point to the CDN.
This results in a slower request until the content is cached on the server.
Pull CDNs minimize storage space on the CDN
Uses:
Sites with heavy traffic work well with pull CDNs, as traffic is spread out more evenly with only recently-requested content remaining on the CDN.