If after installing Apache and starting the server the following message shows in the error logs and the apache server does not start:
hostname nor servname provided, or not known: mod_unique_id: unable to find IPv4 address of xxxxxx
then in httpd.conf disable the line
LoadModule unique_id_module libexec/apache2/mod_unique_id.so
Restart again. This is usually the fix if changing hosts and httpd.conf ServerName entries etc. do not fix the problem.
My friend, thank you! Thank you very much, you saved the day and me countless hours.