The /etc folder on these Linux installations contain a file named inittab - mind you no extensions to the filename. This file contains lots of important parameters & runlevel configurations that the kernel reads while booting and configures the system accordingly. Open this file in your favourite editor and scroll down just a little bit say, till the 18th-20th line (usually) till you find something similar to this:

# Default runlevel. The runlevels used by RHS are:

#

id:3:initdefault:

As you can see the last line id:3:initdefault: specifies WHAT MODE (Graphical/Text/MultiUser etc) to boot the system into. The number "3" which according to the options - is Full multiuser mode - involving all the networking features of Linux, but in a non-graphical environment.