MOSS Administration: Introduction to NetBIOS names and FQDNs

Overview I have recently encountered a problem while installing and configuring Microsoft Office SharePoint Server 2007; and while trying to fix this issue I was confronted by the terminologies NetBIOS and FQDN. My limited networking background was sufficient to proceed in the instructions and fix the problem. But still I was interested in exploring the differences between NetBIOS and FQDN. In this article I present a simple overview on that topic, which I quote from a book called Troubleshooting Microsoft Technologies: The Ultimate Administrator's Repair Manual(Chapter 2 Fundamental Networking). NetBIOS Names versus FQDNs An aspect of TCP/IP networking that is essential to understand is the concepts of NetBIOS names and fully qualified domain names (FQDNs). With computers running TCP/IP, it is much easier to remember a friendly name than the IP address of a system. NetBIOS naming and FQDNs both give you the ability to associate a friendly name with a network object, but the primary difference between the two is how you see the name written. An FQDN is typically computer name.domain name.domain extension.(Example: www.awl.com) A NetBIOS name is a simple name used to represent a system but is limited in size to 15 characters. For the FQDN www.awl.com, its NetBIOS name equivalent would be www. Now consider how many www's there are out there. If we used NetBIOS on the Internet, there would be no way to tell systems apart, and that is why the naming convention for any distributed networked environment has to be fully qualified domain names. Naming Rules Now that you understand the fundamental differences between NetBIOS naming and FQDNs, let's look at the naming rules associated with each. NetBIOS naming rules:

• The name can't begin with a number.
• The name can be no longer than 15 characters.
• The name can use the characters A-Z, a-z, 0-9, hyphens; and is not case sensitive.
• The name can have spaces (a space counts as one character).

FQDN naming rules:

• The name can begin with a number.
• The name can be no longer than 255 characters (domain controllers are limited to 155 characters).
• The name can use the characters A-Z, a-z, hyphens, and is not case sensitive.
• The names cannot have spaces
• Portions of the name are separated by periods (e.g www.microsoft.com)

Name Resoltuion Methods So you have seen that we can use NetBIOS names and FQDNs as easier methods to remember computers. While we can remember names, something has to exist on the network to connect a name to its corresponding IP address. These are the predominent methods:

• Domain Name Service (DNS) - The server that resolves FQDNs to IP addresses.
• Windows Internet Naming Services (WINS) - The server that resolves NetBIOS names to IP addresses.
• Hosts file - The file stored locally on every computer that maps IP addreses to FQDNs.
• LMHosts file - The file stored locally on every computer that maps IP addreses to NetBIOS names.
• Broadcast - A way for your computer to shout out to the network. "Hey does anyone know computer X?" (Routers drop broadcat packets, so broadcasts only work on the subnet connected to the system sending the broadcast. Aslo, broadcasts gobble up netwrok bandwidth)

Finally, I hope this article has provided a basic understanding of NetBIOS names and FQDNs. For much depth explanations, I recommend referring to the book. Samar Hossam