Understanding domain names

As we mention in the preceding section, each device on an IP network is a node. Many nodes are also termed hosts. Generally, a host is a computer, router, or other "smart" device, but any device can be considered a host and have a host name associated with it. In Windows Server 2003, a computer's name as it appears on the LAN is typically its host name. Assume, for example, that your computer's name is tia and that your computer resides in the mcity.us domain. The host name is tia, the domain name is mcity.us, and the Fully Qualified Domain Name (FQDN) of your computer is tia.mcity.us. The FQDN identifies the host's absolute location in the DNS namespace.

Domain names are not limited to a single level, as in the preceding example. Assume that the mcity.us domain comprises several sites, each with its own subdomains. In addition, assume that each domain is divided into three subdomains: east, midwest, and west. The domain names would be east.mcity.us, midwest.mcity.us, and west.mcity.us. These domains could further be divided into subdomains, such as sales.west.mcity.us, support.west.mcity.us, and so on. Taking this example one step further, consider a host named tia in the support.west.mcity.us domain. This host's FQDN would be tia.support.west.mcity.us.

Table 17-1 lists the original top-level domains. Notice that the root of the domain namespace is a null, which is often represented by a dot (.). The dot is omitted from Table 17-1.

Table 17-1: Original Top-Level Domains

Suffix

Purpose

Example

com

Commercial organizations such as businesses

microsoft.com

edu

Educational organizations such as colleges and universities

berkeley.edu

gov

Governmental organizations such as the IRS, SSA, NASA, and so on

nasa.gov

int

International organizations such as NATO

nato.int

mil

Military organizations such as the Army, Navy, and so on

army.mil

net

Networking organizations such as ISPs

mci.net

org

Noncommercial organizations such as the IEEE standards body

ieee.org

Table 17-2 lists new top-level domains.

Table 17-2: New, Additional Top-Level Domains

Suffix

Purpose

Example

aero

Restricted to the air-transport industry

boeing.aero

biz

Businesses

latinaccents.biz

coop

Restricted to co-op organizations or those that serve co-ops

redriver.coop

info

Informational sites

windows.info

museum

Restricted to museums, museum associations, and museum professionals

smithsonian.museum

name

Personal names

boyce.name

pro

Restricted to credential-bearing accountants, lawyers, and doctors

shapiro.pro

us

Individual, businesses, and organizations with a presence in the United States

ford.us

Tip See www. i cann . org for information about the new domain namespaces.

Several other domain types exist in addition to the domain types specified in Tables 17-1 and 17-2. The .us domain, for example, which is listed in the table, is used by governmental, regional, and educational institutions in the United States. Other countries have their own domains, such as .uk for the United Kingdom, .jp for Japan, and so on. These domains are not listed in the table.

NeuStar, based in Washington, D.C., has been assigned authority for the .us domain by the U.S. government. NeuStar's .us Web site provides links to enable you to research, register, and delegate within this domain. Point a Web browser to www.nic.us or www.neustar.us for more information on the .us domain or to request delegation for .us subdomains.

Until a few years ago, an organization called InterNIC was responsible for managing and allocating domain names within the top-level domains. InterNIC, however, became a for-profit business named Network Solutions, forfeiting its monopoly on the domain namespace. Network Solutions still can allocate domain names, however, as can a multitude of other companies on the Internet. To acquire a domain name for your organization, point your Web browser to www.icann.org to locate a domain registrar. Most domain registrars provide features on their Web sites to look up domain names — to determine whether the names are in use or are available, to register new domains, to modify domains, and so on.

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