I couldn't find an answer in the man pages for sysctl. My sysctl.conf file is still at its default state. I'm testing several values and loaded new settings via sysctl -p newsettings.conf. I thought it would be sufficient for reseting to do sysctl -p (which means that it reads the values from sysctl.conf), but a fast sysctl -a | grep domain revealed that they are still the old settings.
Any ideas?
As far as I know there is no "undo" for sysctl -- You need to re-enter the default settings (typically /etc/sysctl.conf simply does not specify defaults, so re-reading it won't revert your changes unless there's an explicit setting).
If you do not know your default settings a reboot will get them back, and you can then list them with sysctl -a (store this somewhere for reference). If you have another mostly-identical machine around you can grab the sysctl -a output from that host instead of rebooting.
Sysctl Defaults
On CentOS 7, look at
/usr/lib/sysctl.d/
to get the default settings that ship with the OS.
