Novell LINUX ENTERPRISE SERVER 11 - ADMINISTRATION Administration Manual page 229

Consider a complete name, such as jupiter.example.com, written in the format
hostname.domain. A full name, referred to as a fully qualified domain name
(FQDN), consists of a hostname and a domain name (example.com). The latter also
includes the top level domain or TLD (com).
TLD assignment has become quite confusing for historical reasons. Traditionally, three-
letter domain names are used in the USA. In the rest of the world, the two-letter ISO
national codes are the standard. In addition to that, longer TLDs were introduced in
2000 that represent certain spheres of activity (for example, .info, .name, .museum).
In the early days of the Internet (before 1990), the file /etc/hosts was used to store
the names of all the machines represented over the Internet. This quickly proved to be
impractical in the face of the rapidly growing number of computers connected to the
Internet. For this reason, a decentralized database was developed to store the hostnames
in a widely distributed manner. This database, similar to the name server, does not have
the data pertaining to all hosts in the Internet readily available, but can dispatch requests
to other name servers.
The top of the hierarchy is occupied by root name servers. These root name servers
manage the top level domains and are run by the Network Information Center (NIC).
Each root name server knows about the name servers responsible for a given top level
http://www
domain. Information about top level domain NICs is available at
.internic.net.
DNS can do more than just resolve hostnames. The name server also knows which host
is receiving e-mails for an entire domain—the mail exchanger (MX).
For your machine to resolve an IP address, it must know about at least one name server
and its IP address. Easily specify such a name server with the help of YaST. If you have
a modem dial-up connection, you may not need to configure a name server manually
at all. The dial-up protocol provides the name server address as the connection is made.
The configuration of name server access with SUSE® Linux Enterprise Server is de-
scribed in Section "Configuring Hostname and DNS" (page 225). Setting up your own
name server is described in Chapter 21, The Domain Name System (page 279).
The protocol whois is closely related to DNS. With this program, quickly find out
who is responsible for any given domain.
Basic Networking 215