Mac OS X Server: HTTP Server Does Not Start From the "On" Button

Turning the Network Settings Preferences 'on' in the control panel will not start the Apache web server. The 'off' button in the control panel turns the Apache HTTP service off, but the 'on' button does not start the server.
You have to restart the server computer in order to start the web server from the control panel. The Apache server can also be started from the command line. This does not require restarting the server computer. To turn the HTTP server on without restarting, type this command in a Terminal window:
Published Date: Feb 18, 2012