Chapter 14: IP Addressing - Zero to Insane in Two Seconds Flat

The Transmission Control Protocol/Internet Protocol (TCP/IP) drives the Internet and makes it accessible around the world. However, TCP/IP is a lot more than just a collection of protocols: Many elements in TCP/IP marry protocols to related services to provide more complete capabilities. Important examples include dynamic address allocation and management, known as the Dynamic Host Configuration Protocol (DHCP), plus domain name to address resolution services, known as Domain Name Service (DNS). In this chapter, you find out about TCP/IP names , addresses, and related standard services, as well as some other related services hosted by Windows Server 2003.

Resolving a Name: TCP/IP and NetBIOS

Whenever you issue a command in Windows Server 2003, you're expected to use the proper syntax. Otherwise, your efforts may not produce the desired results. For example, when you issue a NET USE command from a command prompt, you must enter the server name and a share name, as well as the drive to which you want to map. Therefore, a simple command such as

 NET USE G: \\LANWRIGHTS\APPS 

associates the drive letter G with a share named APPS on the LANWRIGHTS server. If you use the TCP/IP protocol to convey the data involved, the protocol doesn't know how to interpret the name LANWRIGHTS as the server. Instead, it understands Internet Protocol (IP) addresses, such as 172.16.1.7.

If you use TCP/IP on your network, you need some way to convert IP addresses into names and vice versa. Just as the United Nations requires translators so that everyone can communicate, so too does Windows 2003, which is why understanding naming conventions and name-to-address resolution are such an important part of working with TCP/IP on Windows 2003.

NetBIOS names

If you're like most folks, you freeze like a deer in the headlights when you hear the word NetBIOS . Don't worry. Only a small number of people really understand NetBIOS in detail, and figuring out what you need to know is easy.

A NetBIOS name is often called a computer name . When you install Windows Server 2003 on a network, each computer that runs Windows 2003 requires a unique computer name. This allows all NetBIOS-based utilities to identify each machine by its name. When you enter a command that includes a computer name, Windows 2003 knows which computer you're talking about.

If you try to give two devices the same name, you run into trouble like trying to use the same Social Security number for two people. Each time a computer joins the network, it registers its name with a browser service that keeps track of such things. When the second computer with the same name tries to register, it's rejected because that name is already taken. In fact, that machine will be unable to join the network until its name is changed to something unique.

When creating NetBIOS names, you need to work within their limitations, which are as follows :

• NetBIOS names must be between 1 and 15 characters long. (If you have DOS or Windows 3. x machines on your network, they can't recognize NetBIOS names with more than 8 characters.)

• NetBIOS names may not contain any of the characters shown in the following list:

  	double quotation mark
  /	right slash
  \	left slash
  [	left square bracket
  ]	right square bracket
  :	colon
  ;	semicolon
  	vertical slash
  =	equal sign
  +	plus sign
  *	asterisk
  ?	question mark
  <	left angle bracket
  >	right angle bracket

  In addition, dollar signs are not recommended because they have a special meaning. (A NetBIOS name that ends in $ does not appear in a browse list.)

• Don't use lengthy names or put spaces in names. Windows 2003 doesn't care if you use longer names or include embedded spaces, but other networking clients or systems may not be able to handle such uses.

• Choose names that make sense to users and are short and to the point. Don't name machines after their users or locations, especially if users come and go regularly or if machines move around a lot. When it comes to servers, name them to indicate their organizational role or affiliation (for example, Sales, Accounting, or Engineering).

What's in a NetBIOS name, you ask? A NetBIOS name should have a short, clear indication of what's being named so users can recognize what they see. At best, this type of naming convention will make sense without requiring further explanation. At the very least, you can do what we do and put a sticker with the machine's name on each monitor or computer case for identification. You can view a list of your network's NetBIOS names by expanding the My Network Places section of Windows Explorer. See Figure 14-1 for a sample list of NetBIOS names taken from our network (such as W2kpro-1 and Wxppro-2).

Figure 14-1: NetBIOS computer names on our network.

TCP/IP names and addresses

TCP/IP uses a different scheme for names than NetBIOS does. TCP/IP uses 32-bit numbers to construct IP addresses (for example, 172.16.1.11). Each host or node on a TCP/IP network must have a unique IP address.

IP addresses are not meaningful to most humans and are difficult to remember. Therefore, it's helpful to have some way to convert IP addresses to meaningful names. On a Windows Server 2003 network, you use computer names (also known as NetBIOS names). The Internet community uses a different naming convention called domain names. Translation methods , such as Windows Internet Name Service (WINS) and Domain Name Service (DNS) maintain databases for converting an IP address to a computer name (WINS) or a domain name (DNS).

If you've ever used a Web browser on the Internet, you know that you can type a Uniform Resource Locator (URL), such as http://www.lanw.com/, or an IP address, such as 206.224.65.194/ , to obtain access to a Web page. You can do so because the Internet uses DNS to resolve IP addresses to domain names and vice versa. If you type the IP address, the Web browser jumps straight to the address; if you type a domain name, your request goes through a DNS server that resolves the name to an IP address, and then the browser jumps to the address.

In the IP world, the naming scheme you can use is limited if you plan to connect your network directly to the Internet. VeriSign (http://www.verisign.com) is one of many domain name registrars in charge of approving and maintaining the database of "legal" Internet top-level domain names. You can request any domain name you want, but if someone else is using it or has a legitimate claim to a trade or brand name, you won't be able to use it. For example, you probably won't be able to use http://mcdonalds.com or http://cocacola.com as domain names. Or if someone else has already registered xyzcorp.com, you wouldn't be able to use that name, even if your company is named XYZ Corporation.

The format for a typical IP name is host.domainname.suffix . The domain name is something you can't guarantee, but typically represents your organization. The suffix, called a top-level domain , sometimes identifies the country of origin (for example, .ca is Canada and .de is Germany) or the type of organization (.gov is government, .edu is education, .com is a commercial business, .org is a nonprofit organization, and so forth).

Some domain names are more complex; they can take a form such as host.subdomain.domainname.suffix , as in jello.eng.sun.com , where the host name is jello , the subdomain is eng (for engineering), and the domain name is sun (the domain name for Sun Microsystems, Inc.), which is a commercial (.com) entity. The only parts of the name under control of the various Internet domain name registrars (such as VeriSign and other companies and organizations identified at http://www.norid.no/domenenavnbaser/domreg.html) are the domain name and the suffix every domain name must be unique in its entirety to be properly recognized.

Names that include the host part, the domain name, and the suffix (plus any other subdomain information that may apply) are called Fully Qualified Domain Names (FQDNs). To be valid, any FQDN must have a corresponding entry in some DNS server's database that allows it to be translated into a unique numeric IP address. For example, your authors' Web server is named http://www.1anw.com, which resolves into an IP address of 206.224.65.194.

As long as you're completely isolated from the Internet and intend to stay that way, you can assign any names and IP addresses you like on your network. If you ever connect your network to the Internet, however, you'll have to go back and change everything! If your network will be or simply might ever be connected to the Internet, you have one of two options for assigning addresses:

• You can obtain and install valid public IP addresses and domain names now.

  Your Internet Service Provider (ISP) can do this for you. When you obtain a range of IP addresses for your network remember, each computer needs its own unique address, and some computers or devices need multiple addresses (one for each interface) make sure you get enough to leave some room for growth.

• You can (and should) obtain a valid domain name from VeriSign or another domain name registrar, but you can use any of a range of reserved IP addresses, called private IP addresses, to number your networks.

  These addresses may not be used directly on the Internet; they've been set aside for private use. When used in concert with a type of software called Network Address Translation (or NAT for short), this approach requires you to obtain only a small number of public IP addresses but still allows Internet access for every computer on your network. This topic is discussed in more detail later in this chapter in the section "Address translation: The new magic."

To find out more about the process of obtaining a domain name, visit VeriSign's Web site at http://www.verisign.com. The form for researching domain names (determining whether a FQDN is already in use) and registering domain names (applying for a new FQDN) is on the main page. You'll find details on name registration services as well as on directory and database services that support the Internet's distributed collection of DNS servers.