FQDN, which stands for fully qualified domain name, is a unique name that identifies a specific Internet location. It is made up on at least two sections separated by dots. The section contains a series of letters or numbers that are not separated, and sometimes it could be a recognizable word or abbreviation. The order of these sections in the FQDN is of significance, because as one moves from right to left to right each of the sections is representative of a more general level in the Domain Name Server pecking order. Typically, an FQDN has what is called a trailing dot, though most DNS resolvers will regard any domain name that bears a dot as being a FQDN and will automatically add the final dot that is necessary for the root of the DNS tree. In case the domain name doesn’t have a dot, resolvers would treat is as unqualified and would proceed to add a default domain name as well as the final dot. Some Web browsers may also qualify the domain name part of the URL (for Uniform Resource Locator) in the event that the resolver doesn’t find the domain name. The difference between an FQDN and a domain name is the former’s absoluteness, because a default domain name is never added. For a device with a host name “Host” and a default parent default name of blahblah.com, the full domain name would be “Host.blahblah.com.” In this way, the device is fully identified. As it happens, there are many hosts in the world that would be called “Host,” but there can only be one “Host.blahblah.com.” There is a dot at the end of every domain name, so instead of “blahblah.com” you would have “blahblah.com.” This ensures that the name is FQDN.
For those who are already connected to the Internet, an FQDN is already established for their machines. It is easy to find out whether this is the case, by checking the TCP/IP configuration files on the machine in order to identify the FQDN and its components parts (including the host and Internet domain names). This may be accomplished by the following steps:
* Go to the “Control Panel.”
* Go to the network icon just within the control panel window. Double-click it, and this will open the Network Settings window.
* Go to the TCP/IP protocol entry on the Network Software and Adapter’s card list. Open the TCP/IP Configuration window by double-clicking it.
* Open the DNS configuration window by clicking the DNS.
* You will find the host and the domain name for the machine you are using displayed in the fields at the top of the window.
For those not yet connected to the Internet, it is possible that the domain name is not established as yet for their machines. And it will be necessary for those unconnected to get a registered Internet domain as part of the Internet package when they finally get connected to the Internet.
For more information on FQDN read What is FQDN?
http://www.tech-faq.com/fqdn.shtml
