DNS (Domain Name System)
Domain Name Servers: The DNS is a set of distributed databases containing
IP (Internet Protocol) addresses and their corresponding domain names. If you
spend any time on the Internet sending e-mail or browsing the Web, then you use
domain name servers without even realizing it. Domain name servers, or DNS, are
an incredibly important but completely hidden part of the Internet, and they
are fascinating. The DNS system forms one of the largest and most active
distributed databases on the planet. Without DNS, the Internet would shut down
very quickly.
Domain Name Mapping: Each domain name is mapped to a particular
numeric address. Reading the Netsouth domain name www.ncsnet.com
from left to right, the first item (www) is the name of the host
computer itself. The next item (ncsnet) is the second-level
domain name, and usually reflects an organization name. The last item
(com) is a top-level domain name, and describes the organization
who owns the second-level name.
Email Addresses: In an e-mail address such as "support@ncsnet.com",
the domain name follows the @ symbol, and often consists only of
a second-level domain and top-level domain name (ncsnet.com).
IP Addresses: Names like "business.com" are easy for people to remember,
but they don't do machines any good. All of the machines use names called IP
addresses to refer to one another. For example, the machine that we refer to as
"www.business.com" has a specific IP address of the format 111.23.45.255.
Every time you use a domain name, you use the Internet's domain name servers (DNS)
to translate the human-readable domain name into the machine-readable IP address.
During a day of browsing and e-mailing, you might access the domain name
servers hundreds of times!
