Controlling Apache Clients (Prefork MPM)
The request handling behavior just described for the Prefork MPM is controlled by a number of configuration directives. The default values shown in Table 7–3 are from the Ubuntu distribution of Apache; other distributions may have chosen alternative values for their defaults.
Most distributions set these values in the main httpd.conf configuration file;
however, some distributions such as Ubuntu place them in a separate file in the “extra” subdirectory in the Apache configuration folder. For example, on Ubuntu they are found in /etc/apache2/conf/extra/httpd-mpm.conf. You may also need to uncomment an include file line in httpd.conf to get them to load.