Chapter 17. Network Configuration168TipTo change lookup order, edit the /etc/host.conf file. The line order hosts, bindspecifies that /etc/hosts takes precedence over the name servers. Changing the lineto order bind, hosts configures the system to resolve hostnames and IP addressesusing the name servers first. If the IP address cannot be resolved through the nameservers, the system then looks for the IP address in the /etc/hosts file.17.10. Working with ProfilesMultiple logical network devices can be created for each physical hardware device. For example, if youhave one Ethernet card in your system (eth0), you can create logical network devices with differentnicknames and different configuration options, all to be specifically associated with eth0.Logical network devices are different from device aliases. Logical network devices associated with thesame physical device must exist in different profiles and cannot be activated simultaneously. Devicealiases are also associated with the same physical hardware device, but device aliases associatedwith the same physical hardware can be activated at the same time. Refer to Section 17.11, “DeviceAliases” for details about creating device aliases.Profiles can be used to create multiple configuration sets for different networks. A configuration setcan include logical devices as well as hosts and DNS settings. After configuring the profiles, you canuse the Network Administration Tool to switch back and forth between them.By default, there is one profile called Common. To create a new profile, select Profile => New fromthe pull-down menu, and enter a unique name for the profile.You are now modifying the new profile as indicated by the status bar at the bottom of the mainwindow.Click on an existing device already in the list and click the Copy button to copy the existing deviceto a logical network device. If you use the New button, a network alias is created, which is incorrect.To change the properties of the logical device, select it from the list and click Edit. For example, thenickname can be changed to a more descriptive name, such as eth0_office, so that it can berecognized more easily.In the list of devices, there is a column of checkboxes labeled Profile. For each profile, you cancheck or uncheck devices. Only the checked devices are included for the currently selected profile.For example, if you create a logical device named eth0_office in a profile called Office andwant to activate the logical device if the profile is selected, uncheck the eth0 device and check theeth0_office device.For example, Figure 17.16, “Office Profile” shows a profile called Office with the logical deviceeth0_office. It is configured to activate the first Ethernet card using DHCP.
