CDN stands for content delivery network
Most web sites deliver both dynamic and static content from a single server to whole world. This method might be still useful for the web sites which have limited visitors and when visitors come from small geographical region that are close to the server.
However, if you are targeting visitors from all around the world, this method starts to encounter a lot of speed problems due to distance from the server.
Also, if your website has high volume of visitors, delivering static content from the server causes performance issues and errors.
How to prevent this problem?
You use a CDN to serve the static content from a different point.
The Content Delivery Network (CDN) is a group of geographically-distributed servers which deliver static contents with best possible speed.
CDNs are very important for a website performance, but sometimes CDNs can't maintain high performance level all the time. They may become out of service, have latency or encounter any kind of other problems.
To prevent this problem, some CDN services use a multi CDN architecture, that help you achieve a high performance level and %100 uptime.
Multi CDN is a combination of 2 or more CDN networks. image4io uses multi CDN strategy to deliver content more efficiently and with more robust architecture.