Determining Host Configuration Modes
As a network administrator, you configure TCP/IP to run on hosts and routers (if applicable). You can configure these systems to obtain configuration information from files on the local system or from files that are located on other systems on the network. You need the following configuration information:
A system that obtains TCP/IP configuration information from local files operates in local files mode. A system that obtains TCP/IP configuration information from a remote network server operates in network client mode.
Systems That Should Run in Local Files Mode
To run in local files mode, a system must have local copies of the TCP/IP configuration files. These files are described in TCP/IP Configuration Files. The system should have its own disk, though this recommendation is not strictly necessary.
Most servers should run in local files mode. This requirement includes the following servers:
Additionally, routers should run in local files mode.
Systems that function exclusively as print servers do not need to run in local files mode. Whether individual hosts should run in local files mode depends on the size of your network.
If you are running a very small network, the amount of work that is involved in maintaining these files on individual hosts is manageable. If your network serves hundreds of hosts, the task becomes difficult, even with the network divided into a number of administrative subdomains. Thus, for large networks, using local files mode is usually less efficient. However, because routers and servers must be self-sufficient, they should be configured in local files mode.
Network Configuration Servers
Network configuration servers can also function as NFS file servers.
If you are configuring any hosts as network clients, then you must also configure at least one system on your network as a network configuration server. If your network is subnetted, then you must have at least one network configuration server for each subnet with network clients.
Systems That Are Network Clients
Any host that obtains its configuration information from a network configuration server operates in network client mode. Systems that are configured as network clients do not require local copies of the TCP/IP configuration files.
Network client mode simplifies administration of large networks. Network client mode minimizes the number of configuration tasks that you perform on individual hosts. Network client mode assures that all systems on the network adhere to the same configuration standards.
Configurations are not limited to either an all-local-files mode or an all-network-client mode. Routers and servers should always be configured in local mode. For hosts, you can use any combination of local files and network client mode.
IPv4 Network Topology Scenario
Figure 5-1 shows the hosts of a fictitious network with the network number 192.9.200. The network has one network configuration server, which is called sahara. Hosts tenere and nubian have their own disks and run in local files mode. Host faiyum also has a disk, but this system operates in network client mode.
Finally, the system timbuktu is configured as a router. The system includes two network interfaces. The first interface is named timbuktu. This interface belongs to network 192.9.200. The second interface is named timbuktu-201. This interface belongs to network 192.9.201. Both networks are in the organizational domain deserts.worldwide.com. The domain uses local files as its name service.
Figure 5-1 Hosts in an IPv4 Network Topology Scenario