CDNs are probably the biggest consumers of traffic on the internet, but most people never even know about them. But they're vital to ensuring snappy web page load times and smooth video streaming performance.
Supported clients: Whiteboxes, Routers
CDNs are widely used by large websites to distribute static content near to end users. This reduces the burden on the content providers' servers and improves web page load times. Major, well-known CDNs include Akamai, Google and Microsoft. There are a great many smaller CDNs in operation too.
The largest CDN operators will place caches inside ISP networks so that traffic does not even need to leave the ISP network. This is beneficial for both the ISPs (it reduces the load on their transit and peering links) and the CDN operators too (it spreads the content serving burden to a wider array of servers).
CDNs currently supported for testing are as follows:
- Amazon AWS/Cloudfront
- Microsoft Azure
The key metrics captured by the test are as follows:
- TCP connection time
- Download speed
- Object fetch time (lower is better)
- The IP address of the CDN node
Please note that that download speed is not representative of the maximum capacity of the user's broadband connection. An 80KiB transfer is not enough to ramp the line up to full speed. It is instead intended to be indicative of the transfer rate seen for a small object as served by the CDN in question.