Naming Entities on Your Network
After you receive your assigned network IP address and you have given the
IP addresses to your systems, the next task is to assign names
to the hosts. Then you must determine how to handle name services on
your network. You use these names initially when you set up your network
and later when you expand your network through routers, bridges, or PPP.
The TCP/IP protocols locate a system on a network by using its
IP address. However, if you use a recognizable name, then you can easily
identify the system. Therefore, the TCP/IP protocols (and the Solaris OS) require both the
IP address and the host name to uniquely identify a system.
From a TCP/IP perspective, a network is a set of named entities.
A host is an entity with a name. A router is an entity
with a name. The network is an entity with a name. A group
or department in which the network is installed can also be given a
name, as can a division, a region, or a company. In theory, the
hierarchy of names that can be used to identify a network has
virtually no limit. The domain name identifies a domain.
Administering Host Names
Many sites let users pick host names for their machines. Servers also require
at least one host name, which is associated with the IP address of
its primary network interface.
As a system administrator, you must ensure that each host name in
your domain is unique. In other words, no two machines on your network
can both have the name “fred.” However, the machine “fred” might have multiple IP
addresses.
When planning your network, make a list of IP addresses and their
associated host names for easy access during the setup process. The list can
help you verify that all host names are unique.
Selecting a Name Service and Directory Service
The Solaris OS enables you to use three types of name services: local
files, NIS, and DNS. Name services maintain critical information about the machines on
a network, such as the host names, IP addresses, Ethernet addresses, and so
forth. The Solaris OS also gives you the option of using the LDAP
directory service in addition to or instead of a name service. For an
introduction to name services on Solaris, refer to Part I, About Naming and Directory Services, in System Administration Guide: Naming and Directory Services (DNS, NIS, and LDAP).
Network Databases
When you install the operating system, you supply the host name and IP
address of your server, clients, or standalone system as part of the procedure.
The Solaris installation program adds this information into the hosts . This
database is part of a set of network databases that contain information necessary
for TCP/IP operation on your network. The name service that you select for
your network reads these databases.
The configuration of the network databases is critical. Therefore, you need to decide
which name service to use as part of the network planning process. Moreover,
the decision to use name services also affects whether you organize your network
into an administrative domain. Network Databases and the nsswitch.conf File has detailed information on the set of network
databases.
Using NIS or DNS as the Name Service
The NIS and DNS name services maintain network databases on several servers on
the network. System Administration Guide: Naming and Directory Services (DNS, NIS, and LDAP) describes these name services and explains how to configure
the databases. In addition, the guide explain the “namespace” and “administrative domain” concepts in
detail.
Using Local Files as the Name Service
If you do not implement NIS, LDAP, or DNS, the network uses
local files to provide the name service. The term “local files” refers to the
series of files in the /etc directory that the network databases use. The
procedures in this book assume you are using local files for your name
service, unless otherwise indicated.
Note - If you decide to use local files as the name service for
your network, you can set up another name service at a later date.
Domain Names
Many networks organize their hosts and routers into a hierarchy of administrative domains.
If you are using the NIS or DNS name service, you must select
a domain name for your organization that is unique worldwide. To ensure that
your domain name is unique, you should register the domain name with the
InterNIC. If you plan to use DNS, you also need to register your
domain name with the InterNIC.
The domain name structure is hierarchical. A new domain typically is located below
an existing, related domain. For example, the domain name for a subsidiary company
can be located below the domain of the parent company. If the domain
name has no other relationship, an organization can place its domain name directly
under one of the existing top-level domains.
The following are a few examples of top-level domains:
.com – Commercial companies (international in scope)
.edu – Educational institutions (international in scope)
.gov – U.S. government agencies
.fr – France
You select the name that identifies your organization, with the provision that the
name must be unique.
Administrative Subdivisions
The question of administrative subdivisions deals with matters of size and control. The
more hosts and servers that you have in a network, the more complex
your management task. You might want to handle such situations by setting up
additional administrative divisions. Add networks of a particular class. Divide existing networks into
subnets. The decision about setting up administrative subdivisions for your network is determined
by the following factors:
How large is the network?
A single administrative division can handle a single network of several hundred hosts, all in the same physical location and requiring the same administrative services. However, sometimes you should establish several administrative subdivisions. Subdivisions are particularly useful if you have a small network with subnets and the network is scattered over an extensive geographical area.
Do users on the network have similar needs?
For example, you might have a network that is confined to a single building and supports a relatively small number of machines. These machines are divided among a number of subnetworks. Each subnetwork supports groups of users with different needs. In this example, you might use an administrative subdivision for each subnet.
