Serving up content on the internet can be a tricky business. It isn’t just about running a web or app server(s) in an efficient and reliable manner. One of the other critical factors is DNS. You have to understand and optimize how the name the content is advertised under gets translated to the IP address of the content. I don’t want to turn this into a DNS primer, but the two ends of the line of communication are the authoritative DNS server controlled by the domain owner which stores the official translation of the name to the number and the resolving DNS server which acts as a cache and is where the end-user connects to directly. Both ends of the chain have their own idiosyncrasies which can affect how quickly and reliably your content gets delivered.
On the end-user side, I just read an article about how public DNS providers like OpenDNS and Google are breaking the internet. OK, maybe not breaking the internet, but the public DNS providers are confusing CDN location-based algorithms. The article is here: http://www.sajalkayan.com/in-a-cdnd-world-opendns-is-the-enemy.html and I recommend strongly that both content providers and content consumers read it.
The summary is that some CDN algorithms use the ip address (and location) of the DNS server making the request and if that DNS server is nowhere near the end-user on the internet, the end-user will get served content from farther away and will get that content slower than desired. The conclusion is that an end-user should always use a DNS server located as close as possible network-wise, usually that ends up being a DNS server of the network provider.
That is good advice for the end-user, but what about the content provider? If you flip this around and come at DNS from the content provider’s point of view who doesn’t use CDN, you want to make sure that when a DNS request is made, that your authoritative DNS server gets the ip address as fast and reliably as possible back to the end-user.
SoftLayer has built out authoritative DNS farms in all our Datacenters and Network POPs and anycasted the ip addresses for the name servers. What that means is that SoftLayer customers – who get to use our DNS for free – can have their authoritative domain services hosted at all 10 points in North America and through the routing optimization inherent in the internet, the name to number conversion for those domains will happen as close as possible to the end-user and the results will be delivered as quickly as possible.
One very important goal of every content provider is to get the end-user the best experience as possible. Understanding how the internet works from the end-user and well as the server-side is critical. It doesn’t matter how good your content or app is if the end-user has a poor experience.