I had a conversation recently with @maartenballiauw about the new Azure CDN and how much of an improvement it can make to serving web content; primarily an improvement in last mile for your customers.
He’s put together an awesome slidedeck that he’s given at TechEd and I thought I’d share again. On slide 14 there’s a quote from me
The quote “The Internet sucks and so does your server” is a simple way to think of the problem domain. Due to things like geographic distribution causes unavoidable speed of light latency, compounded by the need to make multiple TCP requests underlying a HTTP request; things like embedding cookies in each request, bloating its weight; things like browsers limiting the number concurrent request: due to things like these, the Internet is weak over distance. Using a CDN fixes this by move some data (often static or semi-static) close to the requestor. And always remember, even if the internet doesn’t suck (a closer datacenter, no cookies, future browsers) sending traffic to a web server increases the load on expensive application capable servers. You can use the CDN to lower the cost of your app by decreasing the load on important, functional servers and pushing it to a content delivery server.