Who are Akamai ?

Akamai Technologies was founded in 1998 to provide a distributed computing platform for global Internet content and application delivery. The word Akamai in Hawaiian means smart or intelligent.

Akamai has developed a global array of interconnected servers that cache content supplied by its Internet customers. This way the content is physically much closer to the Internet user who wants to access it. Big companies purchase Akamai's service to speed up the upload time of their pages.
Akamai make use of specialized DNS servers and high caching web servers to lower latency for end users.

How does this work ?

Akamai has developed proprietary, patent-pending algorithms to determine the optimal server for a given end user.  These algorithms drive a multi-level DNS-based process that identifies a specific server to contact.  When a user makes a request for the IP address of a given Akamai server (eg.a9.g.akamai.net), the request is initially routed to an Akamai High-Level DNS (HLDNS) server.  Using constantly updated information about the state of the Internet and the network location of the end user, the HLDNS server determines an optimal region/data center to serve the end user from.  The HLDNS server then returns a list of Akamai Low-Level DNS (LLDNS) servers within that optimal region.  When a request is made to the LLDNS server, it uses information about locally available servers and the demand on them, load balances the incoming requests, and makes a determination as to which server is the optimal one.  The LLDNS server then returns the IP address of the optimal server, and the user can then request content from that server.

Below shows this process broken down into steps,

1. User makes a DNS request for the IP address of a given Akami server.
2. Request is routed to an Akamai High-Level DNS (HLDNS) server.
3. Using end user location and internet state information the HLDNS server derives an optimal region to serve the end user from. 
4. The HLDNS server returns a list of Akamai Low-Level DNS (LLDNS) servers within that optimal region. 
5. A request is then made to the LLDNS server. The LLDNS determines an optimal server and responds to the IP.
6. With the resolved (obtained) IP the user then connects to the server.