mod_unique_id unable to find IPv4 address - IBM HTTP Server not starting

There might be several causes of this issue, why after starting the IHS there is no process running in the system.

# ./apachectl start
#ps -ef | grep httpd
#

No errors thrown, no process running. Even config test runs fine:

$./apachectl configtest

Syntax OK

We could check if it is SELinux issue, but we will check the logs first:

#tail error_log

[Sun Feb 09 17:31:40 2014] [alert] (EAI 2)Name or service not known: mod_unique_id: unable to find IPv4 address of "test0"

The main reason for that is most probably your hostname is not defined in the /etc/hosts file.

Either you have to change your hostname to "localhost" or add the "test0" to the /etc/hosts file.