It used to be that when you booted most linuxes, you would boot into runlevel 6, unless you did something during the bootloading to change the runlevel,.
The process would then look in /etc/init/rcX.d (IIRC) where X was the runlevel, and execute all the scripts begining with S in dictionary sorted order (so S01xxx ran before S20yyy).
When you went through the shutdown procedure the scripts beginning with K would be run and IIRC in reverse dictionary sort order.
Now things have changed the rcX.d directories have been moved to /etc and an /etc/rcS.d has been added, and the default runlevel is 2.
Unfortunately until now I haven't been following the changes. Can someone please describe the boot and shutdown process for runlevel 2 in present systems?