Domains, Hosts, Proxy Servers and DNS
Overview of the basic elements of the world wide web
Domain
A domain is a web site whose name is registered. Another way of looking at a domain is as a main web site and all its sub-sites and links. For example, www.google.com is a domain. A domain is a logical concept; a domain need not necessarily be hooked to a single computer. On the other hand, many computers may together host a large domain.
Host
A host is a computer system with a registered ip address. A host may contain all the files related to one or more domains and thus be the network destination of all requests for the domain. In this case it is said to 'host' the domains.
Proxy Server
A proxy server is an Internet server that sits between the client and the actual server. It is often on the same network as the client computer. In order to save time and bandwidth, the proxy server fulfills as many requests form the client as it can and only passes requests it cannot fulfill to the actual server . For example, the proxy server may store a web page that the user requests over and over again over a session . The proxy may intercept any request to the server for the page and fulfill the request on its own. Most large websites and domains have proxies in strategic high traffic locations.
Domain Name System (DNS)
One of the most important functions of DNS is the translation of IP addresses to easy to remember Domain Names like 'www.yahoo.com' or 'www.google.com'. E-mail addresses are also handled by DNS. A Domain Name Server contains a database with a table that maps Domain Names to corresponding IP addresses. A request for a connection to a domain is sent to this server and the corresponding IP Address is looked up in order to find the actual location of the resource.
