Red Hat ENTERPRISE LINUX 5 - DEPLOYMENT Deployment Manual page 214

Chapter 15. Network Configuration
When your system tries to resolve a hostname to an IP address or tries to determine the hostname
for an IP address, it refers to the /etc/hosts file before using the name servers (if you are using the
default Red Hat Enterprise Linux configuration). If the IP address is listed in the /etc/hosts file, the
name servers are not used. If your network contains computers whose IP addresses are not listed in
DNS, it is recommended that you add them to the /etc/hosts file.
To add an entry to the /etc/hosts file, go to the Hosts tab, click the New button on the toolbar,
provide the requested information, and click OK. Select File > Save or press Ctrl+S to save the
changes to the /etc/hosts file. The network or network services do not need to be restarted since
the current version of the file is referred to each time an address is resolved.
Warning
Do not remove the localhost entry. Even if the system does not have a network
connection or have a network connection running constantly, some programs need to
connect to the system via the localhost loopback interface.
Figure 15.19. Hosts Configuration
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