I couldn't find an answer in the man pages for sysctl. My sysctl.conf file is still at it's default state, I'm testing several values and loaded new settings via
sysctl -p newsettings.conf. I though 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 there are still the old settings.