The principal location for system configuration information is within /etc/rc.conf. This file contains a wide range of configuration information, principally used at system startup to configure the system. Its name directly implies this; it is configuration information for the rc* files.
An administrator should make entries in the rc.conf file to override the default settings from /etc/defaults/rc.conf. The defaults file should not be copied verbatim to /etc - it contains default values, not examples. All system-specific changes should be made in the rc.conf file itself.
A number of strategies may be applied in clustered applications to separate site-wide configuration from system-specific configuration in order to keep administration overhead down. The recommended approach is to place system-specific configuration into the /etc/rc.conf.local file. For example:
sshd_enable="YES" keyrate="fast" defaultrouter="10.1.1.254"
hostname="node1.example.org" ifconfig_fxp0="inet 10.1.1.1/8"
The rc.conf file can then be distributed to every system using rsync or a similar program, while the rc.conf.local file remains unique.
Upgrading the system using sysinstall(8) or make world will not overwrite the rc.conf file, so system configuration information will not be lost.