The hosts file is a file used to store information on where to find a node on a computer network. This file maps hostnames to IP addresses. The hosts file is used as a supplement to (or instead of) the domain name system on networks of varying sizes. This file is (unlike DNS) under the control of the root user of a server. In Solaris it is present in /etc directory.
It is very important that the /etc/hosts file of your server be in this format:
IP address hostname.domainname hostname (without domain name)
Many of the Apps DBA utilities give strange errors if the /etc/hosts file is not in the above format. One such error is described in metalink note 337741.1
If you do adcfgclone.pl dbTechStack on a server with incorrect format in /etc/hosts, the following error is logged:
java.lang.NullPointerException at oracle.apps.ad.util.SystemCheck.getDomainName(SystemCheck.java:1684)
The solution is simple. You need to correct the format of your /etc/hosts file.