Allied Telesis AT-8100 Series - Manual (Page 358)

Chapter 17: Domain Name System (DNS)
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Overview
The Domain Name System (DNS) is a naming system that allows you to
access remote systems using host names that consist of text or text-
based rather than IP addresses. DNS creates a mapping between a
domain name, such as “www.alliedtelesis.com,” and its IP address, for
example, 207.135.120.89. These mappings are held on DNS servers.
To access remote systems using domain names instead of IP addresses,
you must have a DNS server on your network and configure DNS servers
on the switch.
Domain name
parts
Domain names, such as “www.alliedtelesis.com,” consist of two or more
name segments. The format of a domain name is the same as the host
portion of a Uniform Resource Locator (URL), and each segment is
separated by a period.
The hierarchy of a domain name descends from right to left. The segment
on the far right is a top-level domain name shared by many hosts. For
example, the “alliedtelesis” of “www.alliedtelssis.com” belongs to the top-
level domain “com” and the “www” belongs to the “alliedtelesis”.
The following diagram shows an example of DNS hierarchy.
Figure 81. DNS Hierarchy
Server Hierarchy A network of domain name servers maintains the mappings between
domain names and their IP addresses. This network operates in a
hierarchy that is similar to the structure of the domain names. When a
local DNS server cannot resolve your request, it sends the request to a
higher level DNS server.