RHCE Objectives: Use /proc/sys and sysctl to modify and set kernel runtime parameters.
This is all pretty normal work. In RH6 you’d manually edit the /etc/sysctl.conf file to make changes and run sysctl -p to reload the changes or reboot of course. Running sysctl -a shows all the variables (also located in /proc/sys in various subdirectories such as ‘kernel’, hint hint).
RH7 will let you modify the same sysctl.conf file but per the comments, will accept changes in /usr/lib/sysctl.d/00-system.conf (location of default settings) or /etc/sysctl.d/name.conf (such as 00-kernel.conf for kernel settings). The files are numbered similar to the rc.3 files where 00 is the first loaded file and 99 is the last loaded file. This assumes a reason for loading settings in some order.