What's on RHEL the cause which Apache (HTTPD) is installed on the folder "/opt/middleware/httpd/", instead the usual installation folder? What should I apply on my server to have this similar feature, since I am trying to replicate a client environment.
SnapOverflow
This is not a standard httpd installation. It was installed by some third party. You may find it quite difficult to identify the third party without help from the client. You can try poking around for clues, but if you want to be sure you will need to ask the client what this is and why they have done it instead of using the normal httpd included with RHEL.