Chapter 18. AS/400 Domain Name System (DNS)
The Domain Name System (DNS) is an advanced system for managing the host
names that are associated with Internet Protocol (IP) addresses on TCP/IP
networks.
Material on DNS is covered in the AS/400e Information Center under the TCP/IP
topic. For more information see “TCP/IP Topicsin the Information Center” on
page xv.
On AS/400, DNS configuration is only available throughAS/400 Operations
Navigator. Operations Navigator is a graphical user interface, and a part of Client
Access for Windows 95/NT.
For a list of recommended DNS publications, see “Additional DNS documentation”
on page 422.

How DNS works

Material on DNS is covered in the AS/400e Information Center under the TCP/IP
topic. For more information see “TCP/IP Topicsin the Information Center” on
page xv.See “Additional DNS documentation” on page 422 for a list of DNS
publications that contain more detailed information.
The Domain Name System (DNS) was developed to eliminate the problems and
limitations of using host tables only to resolve host names on large TCP/IP
networks. DNS is the naming service of intranets and the Internet. Virtually all
TCP/IP software, including electronic mail, now uses DNS. Applications such as
Telnet,File Transfer Protocol (FTP), and HyperText Transfer Protocol (HTTP)
browsers use DNS as well.
What does DNS do?
The primary job of DNS is to translate TCP/IP host names to Internet Protocol (IP)
addresses. Host names are easy for people to remember, but IP addresses are
what TCP/IP uses to make connections between hosts across the network.
Name resolution and mapping
DNS translates or resolves host names to IP addresses. It can also resolve an IP
address to a host name. When DNS associates an IP address to a host name, the
IP address is said to be mapped to the host name.
What is DNS?
DNS is a system; not one thing, but many. It is a method of logically dividing
TCP/IP networks into manageable units that are called domains. It organizes these
units or domains into a hierarchy whose structure is similar to the roots of a tree. It
is a method for naming both the domains in the hierarchy and the hosts in the
domains, so that no two names are identical.
DNS is a distributed database
© Copyright IBM Corp. 1997, 1999 421
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