Names and Locations

The first thing the browser has to do is to establish a network connection to the machine where the document lives. To do that, it first has to find the network location of the host www.google.com (‘host’ is short for ‘host machine’ or ‘network host'; www.google.org is a typical hostname). The corresponding location is actually a number called an IP address (we'll explain the ‘IP’ part of this term later).

To do this, the browser queries a program called a name server. The name server may live on your machine, but it's more likely to run on a service machine that yours talks to. When you sign up with an ISP, part of your setup procedure will almost certainly involve telling the Internet software the IP address of a nameserver on the ISP's network.

The name servers on different machines talk to each other, exchanging and keeping up to date all the information needed to resolve hostnames (map them to IP addresses). The nameserver may query three or four different sites across the network in the process of resolving www.google.com, but this usually happens very quickly (as in less than a second). The nameserver will tell the browser that www.google.com IP address is 64.233.167.99; knowing this, the machine will be able to exchange bits with www.google.com directly.