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Uniform Resource Locator (URL)

Today the most common way of connecting to a site on the Internet is to use a URL. This essentially has two parts

  • The connection's protocol e.g. http and ftp
  • The domain address consisting of server name and full domain

Example

//www.sqa.org.uk

http hypertext transfer protocol
:// Separates protocol from domain name
www server name - www commonly used for web servers
sqa.org.uk The sub domain name sqa which is registered in the sub domain org which is registered in the top level domain uk


How this all works

Let's assume you have entered the example address above into a browser from a home computer. How is the IP address found?

The request is sent to the DNS server listed in the IP configuration

If the name is not in the DNS lookup table, it will forward the request on to the next DNS in the hierarchy (e.g. from local router, to ISP) and so on.

In the worst-case scenario, it may even reach the uk domain table (this has all of the registered sub domains). From here it could be forwarded to the .org table and hence to the network hosting the domain sqa.org.uk.

Next: NSLookup Activity