The Anatomy of a Web Session
Getting a single object, such as an image, from a web server to a visitor’s browser is the work of many components that find, assemble, deliver, and present the content. They include:
A DNS server that transforms the URL of a website (www.example.com) into an Internet Protocol (IP) address (10.2.3.4).
Internet service providers (ISPs) that manage routes across the Internet.
Routers and switches between the client and the data center that forward packets.
A load balancer that insulates servers from the Web on many larger websites.
Servers and other web infrastructure that respond to requests for content. These include web servers that assemble content, application servers that handle dynamic content, and database servers that store, forward, and delete content.
That’s just for a single object. It gets more complicated for whole pages, and more so for visits.