4.4.1. Edit the Host File
Using a text editor, open the hosts file on every host in your cluster. For example:
vi /etc/hosts
Add a line for each host in your cluster. The line should consist of the IP address and the FQDN. For example:
1.2.3.4
<fully.qualified.domain.name>Important Do not remove the following two lines from your hosts file. Removing or editing the following lines may cause various programs that require network functionality to fail.
127.0.0.1 localhost.localdomain localhost
::1 localhost6.localdomain6 localhost6