CDN (Content Delivery Network)

• should spread across the geo location of the potential users
• only put static data on them
• if the content and resource is public, it can be cached on CDNs

Push CDN

• push the data from origin server to other servers at the time when data is created

Pull CDN

• The CDN would only pull data when user makes request on the CDN server
• check wether it is cached on the CDN or not - like cache
  • A time-to-live (TTL) determines how long content is cached.

Disadvantages

• CDN cost could be significantly dependent on traffic
  • Should be weighed with addition costs of not using a CDN
• Content might be stale if updated before TTL expires it
• CDNs require changing URLs for static content to point to the CDN.