From 2.0.5R to 2.2.1R, the primary configuration file is /etc/sysconfig. All the options are to be specified in this file and other files such as /etc/rc (see rc(8)) and /etc/netstart just include it.
Look in the /etc/sysconfig file and change the value to match your system. This file is filled with comments to show what to put in there.
In post-2.2.1 and 3.0, /etc/sysconfig was renamed to a more self-describing rc.conf(5) file and the syntax cleaned up a bit in the process. /etc/netstart was also renamed to /etc/rc.network so that all files could be copied with a cp /usr/src/etc/rc* /etc command.
And, in 3.1 and later, /etc/rc.conf has been moved to /etc/defaults/rc.conf. Do not edit this file! Instead, if there is any entry in /etc/defaults/rc.conf that you want to change, you should copy the line into /etc/rc.conf and change it there.
For example, if you wish to start named, the DNS server included with FreeBSD in FreeBSD 3.1 or later, all you need to do is:
# echo named_enable="YES" >> /etc/rc.conf
To start up local services in FreeBSD 3.1 or later, place shell scripts in the /usr/local/etc/rc.d directory. These shell scripts should be set executable, and end with a .sh. In FreeBSD 3.0 and earlier releases, you should edit the /etc/rc.local file.
The /etc/rc.serial is for serial port initialization (e.g. locking the port characteristics, and so on.).
The /etc/rc.i386 is for Intel-specifics settings, such as iBCS2 emulation or the PC system console configuration.