Note this is not a ‘primer’ article. For more basic information, click here:
What is a CDN?
How Does a CDN Work?
A CDN uses performance metrics to serve the traffic to the end users, once the end users makes a request the CDN will calculate which server is the optimal to serve that traffic taking into account things like:
- Network Proximity
- Server Load
- Content Availability
The request flow will work as follows:
- Stage 1: End user request > CDN assigns the EDGE Server to serve the traffic > if the content is on the Server then it will be served to the end user
- Stage 2: If the Edge Server does not have the content > The request will be forwarded to the parent server, if the content is found then it is sent to the edge and end user
- Stage 3: If both the edge and parent servers do not have the content > then request is sent to the origin server > then both the parent and the edge server will store the content to be served to other end users if requested
What is an Edge Server?
What is a Parent Server?
The parent servers will live in between the Edge Server and the Origin, these servers will be used to store and deliver assets to the different edge servers from different regions, this will improve Offload to the origin by having multiple layers of caching.
What are the benefits of using a CDN?
Faster delivery of assets:
- Optimal server will be used to deliver the content
- Caching of assets closer to the end users
- CDN will absorb the high volume of users and requests accessing your content, offloading your origin and bandwidth requirements
- Reduction of rebuffering
- Multiple format support: HLS, DASH, CMAF
- CDNs constantly monitor the network to ensure optimal paths are used to reach the origin when necessary
- Your origin will be protected by the CDN it will never be exposed to the world
- Attacks will hit the CDN not your origin
- CDN Tokenization will help you protect your content against piracy by encrypting the Manifest and Child playlists with a Short and Long tokens
- Short token used to encrypt the child playlists, this token is refreshed every X amount of seconds
- Long Token does not change in several minutes and it is stored in a cookie, as this is intended for the master playlist
- CORS headers, a CDN will not serve the content from domains that are not authorized to access the assets
- More than 240,000 servers across the world are available to deliver your assets
- CDN networks are monitored to ensure the health of all regions
- Offload to your origin will mean a more stable origin with less resources from your end
- Even if your origin goes down the CDN can still deliver the content that is cached on the edge servers (stale content)
- Even during large events a CDN will use as many edge servers as required in order to deliver your assets without affecting your origin, hence protecting your origin from going down
- You can have multiple origins and use the CDN to load balance across them
In conclusion, using a CDN not only will increase your security, stability and worldwide presence, it will also enable you to save in hardware deployments and bandwidth. It also translates to a better user experience and quality of service, having the power of thousands of servers spread across the globe available to deliver your content as needed.
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