If you are using a computer with multiple home alias, you can set this variable to point to the host name of the computer on which you are installing Oracle Database.
While installing Enterprise Manager or related components on Multi-homed (Multi-IP) machines, that is, a machine having multiple IP addresses, hostname will be derived from:
- ORACLE_HOSTNAME environment variable if it is set
- else the first name in the host file (/etc/hosts for Linux)
will be considered for installation purposes.